Ubuntu – Can’t get nVidia drivers working with 16.04, logs out right after login

I have installed Ubuntu 16.04 beta 2 on Monday, Apr 18th. When I try to install nvidia-current, nvidia-361 or the version that jockey installs, either lightdm fails to start entirely or I can't get past the login window. When I log in, lightdm.log reports that I have logged in successfully, for some reasons it shows the sound volume I have set and then it returns back to the login screen.

I have a laptop with hybrid nVidia/Intel graphics with the Optimus technology (I don't really need GPU switching, but I want nVidia to run properly), the exact nVidia model is GT630M.

Here is Xorg.0.log:

[    41.529] 
X.Org X Server 1.18.3
Release Date: 2016-04-04
[    41.529] X Protocol Version 11, Revision 0
[    41.529] Build Operating System: Linux 3.13.0-85-generic x86_64 Ubuntu
[    41.529] Current Operating System: Linux dugi 4.4.0-21-generic #37-Ubuntu SMP Mon Apr 18 18:33:37 UTC 2016 x86_64
[    41.529] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.4.0-21-generic root=UUID=77b76089-cd8b-4d0c-b074-1ec581c0a8a9 ro quiet splash
[    41.529] Build Date: 07 April 2016  09:18:50AM
[    41.529] xorg-server 2:1.18.3-1ubuntu2 (For technical support please see http://www.ubuntu.com/support) 
[    41.529] Current version of pixman: 0.33.6
[    41.529]    Before reporting problems, check http://wiki.x.org
    to make sure that you have the latest version.
[    41.529] Markers: (--) probed, (**) from config file, (==) default setting,
    (++) from command line, (!!) notice, (II) informational,
    (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
[    41.529] (==) Log file: "/var/log/Xorg.0.log", Time: Fri Apr 22 00:40:13 2016
[    41.530] (==) Using system config directory "/usr/share/X11/xorg.conf.d"
[    41.530] (==) No Layout section.  Using the first Screen section.
[    41.530] (==) No screen section available. Using defaults.
[    41.530] (**) |-->Screen "Default Screen Section" (0)
[    41.530] (**) |   |-->Monitor "<default monitor>"
[    41.530] (==) No monitor specified for screen "Default Screen Section".
    Using a default monitor configuration.
[    41.530] (==) Automatically adding devices
[    41.530] (==) Automatically enabling devices
[    41.530] (==) Automatically adding GPU devices
[    41.530] (==) Max clients allowed: 256, resource mask: 0x1fffff
[    41.530] (WW) The directory "/usr/share/fonts/X11/cyrillic" does not exist.
[    41.530]    Entry deleted from font path.
[    41.530] (WW) The directory "/usr/share/fonts/X11/100dpi/" does not exist.
[    41.530]    Entry deleted from font path.
[    41.530] (WW) The directory "/usr/share/fonts/X11/75dpi/" does not exist.
[    41.530]    Entry deleted from font path.
[    41.530] (WW) The directory "/usr/share/fonts/X11/100dpi" does not exist.
[    41.530]    Entry deleted from font path.
[    41.530] (WW) The directory "/usr/share/fonts/X11/75dpi" does not exist.
[    41.530]    Entry deleted from font path.
[    41.530] (==) FontPath set to:
    /usr/share/fonts/X11/misc,
    /usr/share/fonts/X11/Type1,
    built-ins
[    41.530] (==) ModulePath set to "/usr/lib/x86_64-linux-gnu/xorg/extra-modules,/usr/lib/xorg/extra-modules,/usr/lib/xorg/modules"
[    41.530] (II) The server relies on udev to provide the list of input devices.
    If no devices become available, reconfigure udev or disable AutoAddDevices.
[    41.530] (II) Loader magic: 0x55a83676cda0
[    41.530] (II) Module ABI versions:
[    41.530]    X.Org ANSI C Emulation: 0.4
[    41.530]    X.Org Video Driver: 20.0
[    41.530]    X.Org XInput driver : 22.1
[    41.530]    X.Org Server Extension : 9.0
[    41.530] (++) using VT number 7

[    41.530] (II) systemd-logind: logind integration requires -keeptty and -keeptty was not provided, disabling logind integration
[    41.531] (II) xfree86: Adding drm device (/dev/dri/card0)
[    41.532] (--) PCI:*(0:0:2:0) 8086:0166:1028:0590 rev 9, Mem @ 0xf7400000/4194304, 0xd0000000/268435456, I/O @ 0x0000f000/64
[    41.532] (WW) "glamoregl" will not be loaded unless you've specified it to be loaded elsewhere.
[    41.532] (II) "glx" will be loaded by default.
[    41.532] (II) LoadModule: "glx"
[    41.532] (II) Loading /usr/lib/x86_64-linux-gnu/xorg/extra-modules/libglx.so
[    41.537] (II) Module glx: vendor="NVIDIA Corporation"
[    41.537]    compiled for 4.0.2, module version = 1.0.0
[    41.537]    Module class: X.Org Server Extension
[    41.537] (II) NVIDIA GLX Module  304.131  Sun Nov  8 22:03:20 PST 2015
[    41.537] (==) Matched intel as autoconfigured driver 0
[    41.537] (==) Matched intel as autoconfigured driver 1
[    41.537] (==) Matched modesetting as autoconfigured driver 2
[    41.537] (==) Matched fbdev as autoconfigured driver 3
[    41.537] (==) Matched vesa as autoconfigured driver 4
[    41.537] (==) Assigned the driver to the xf86ConfigLayout
[    41.537] (II) LoadModule: "intel"
[    41.537] (II) Loading /usr/lib/xorg/modules/drivers/intel_drv.so
[    41.537] (II) Module intel: vendor="X.Org Foundation"
[    41.537]    compiled for 1.18.1, module version = 2.99.917
[    41.537]    Module class: X.Org Video Driver
[    41.537]    ABI class: X.Org Video Driver, version 20.0
[    41.537] (II) LoadModule: "modesetting"
[    41.537] (II) Loading /usr/lib/xorg/modules/drivers/modesetting_drv.so
[    41.537] (II) Module modesetting: vendor="X.Org Foundation"
[    41.537]    compiled for 1.18.3, module version = 1.18.3
[    41.537]    Module class: X.Org Video Driver
[    41.537]    ABI class: X.Org Video Driver, version 20.0
[    41.537] (II) LoadModule: "fbdev"
[    41.538] (II) Loading /usr/lib/xorg/modules/drivers/fbdev_drv.so
[    41.538] (II) Module fbdev: vendor="X.Org Foundation"
[    41.538]    compiled for 1.18.1, module version = 0.4.4
[    41.538]    Module class: X.Org Video Driver
[    41.538]    ABI class: X.Org Video Driver, version 20.0
[    41.538] (II) LoadModule: "vesa"
[    41.538] (II) Loading /usr/lib/xorg/modules/drivers/vesa_drv.so
[    41.538] (II) Module vesa: vendor="X.Org Foundation"
[    41.538]    compiled for 1.18.1, module version = 2.3.4
[    41.538]    Module class: X.Org Video Driver
[    41.538]    ABI class: X.Org Video Driver, version 20.0
[    41.538] (II) intel: Driver for Intel(R) Integrated Graphics Chipsets:
    i810, i810-dc100, i810e, i815, i830M, 845G, 854, 852GM/855GM, 865G,
    915G, E7221 (i915), 915GM, 945G, 945GM, 945GME, Pineview GM,
    Pineview G, 965G, G35, 965Q, 946GZ, 965GM, 965GME/GLE, G33, Q35, Q33,
    GM45, 4 Series, G45/G43, Q45/Q43, G41, B43
[    41.538] (II) intel: Driver for Intel(R) HD Graphics: 2000-6000
[    41.538] (II) intel: Driver for Intel(R) Iris(TM) Graphics: 5100, 6100
[    41.538] (II) intel: Driver for Intel(R) Iris(TM) Pro Graphics: 5200, 6200, P6300
[    41.538] (II) modesetting: Driver for Modesetting Kernel Drivers: kms
[    41.538] (II) FBDEV: driver for framebuffer: fbdev
[    41.538] (II) VESA: driver for VESA chipsets: vesa
[    41.538] (II) intel(0): Using Kernel Mode Setting driver: i915, version 1.6.0 20151010
[    41.538] (II) intel(0): SNA compiled: xserver-xorg-video-intel 2:2.99.917+git20160325-1ubuntu1 (Timo Aaltonen <tjaalton@debian.org>)
[    41.538] (II) intel(0): SNA compiled for use with valgrind
[    41.538] (WW) Falling back to old probe method for modesetting
[    41.538] (WW) Falling back to old probe method for fbdev
[    41.538] (II) Loading sub module "fbdevhw"
[    41.538] (II) LoadModule: "fbdevhw"
[    41.538] (II) Loading /usr/lib/xorg/modules/libfbdevhw.so
[    41.538] (II) Module fbdevhw: vendor="X.Org Foundation"
[    41.538]    compiled for 1.18.3, module version = 0.0.2
[    41.538]    ABI class: X.Org Video Driver, version 20.0
[    41.538] (WW) Falling back to old probe method for vesa
[    41.539] (--) intel(0): Integrated Graphics Chipset: Intel(R) HD Graphics 4000
[    41.539] (--) intel(0): CPU: x86-64, sse2, sse3, ssse3, sse4.1, sse4.2, avx; using a maximum of 2 threads
[    41.539] (II) intel(0): Creating default Display subsection in Screen section
    "Default Screen Section" for depth/fbbpp 24/32
[    41.539] (==) intel(0): Depth 24, (--) framebuffer bpp 32
[    41.539] (==) intel(0): RGB weight 888
[    41.539] (==) intel(0): Default visual is TrueColor
[    41.539] (II) intel(0): Output LVDS1 has no monitor section
[    41.552] (--) intel(0): Found backlight control interface intel_backlight (type 'raw') for output LVDS1
[    41.552] (II) intel(0): Enabled output LVDS1
[    41.552] (II) intel(0): Output VGA1 has no monitor section
[    41.552] (II) intel(0): Enabled output VGA1
[    41.552] (II) intel(0): Output HDMI1 has no monitor section
[    41.552] (II) intel(0): Enabled output HDMI1
[    41.552] (II) intel(0): Output DP1 has no monitor section
[    41.552] (II) intel(0): Enabled output DP1
[    41.552] (--) intel(0): Using a maximum size of 256x256 for hardware cursors
[    41.552] (II) intel(0): Output VIRTUAL1 has no monitor section
[    41.552] (II) intel(0): Enabled output VIRTUAL1
[    41.552] (--) intel(0): Output LVDS1 using initial mode 1366x768 on pipe 0
[    41.552] (==) intel(0): TearFree disabled
[    41.552] (==) intel(0): DPI set to (96, 96)
[    41.552] (II) Loading sub module "dri2"
[    41.552] (II) LoadModule: "dri2"
[    41.552] (II) Module "dri2" already built-in
[    41.552] (II) Loading sub module "present"
[    41.552] (II) LoadModule: "present"
[    41.552] (II) Module "present" already built-in
[    41.552] (II) UnloadModule: "modesetting"
[    41.552] (II) Unloading modesetting
[    41.552] (II) UnloadModule: "fbdev"
[    41.552] (II) Unloading fbdev
[    41.553] (II) UnloadSubModule: "fbdevhw"
[    41.553] (II) Unloading fbdevhw
[    41.553] (II) UnloadModule: "vesa"
[    41.553] (II) Unloading vesa
[    41.553] (==) Depth 24 pixmap format is 32 bpp
[    41.553] (II) intel(0): SNA initialized with Ivybridge (gen7, gt2) backend
[    41.553] (==) intel(0): Backing store enabled
[    41.553] (==) intel(0): Silken mouse enabled
[    41.553] (II) intel(0): HW Cursor enabled
[    41.553] (II) intel(0): RandR 1.2 enabled, ignore the following RandR disabled message.
[    41.553] (==) intel(0): DPMS enabled
[    41.553] (==) intel(0): Display hotplug detection enabled
[    41.553] (II) intel(0): [DRI2] Setup complete
[    41.553] (II) intel(0): [DRI2]   DRI driver: i965
[    41.553] (II) intel(0): [DRI2]   VDPAU driver: va_gl
[    41.553] (II) intel(0): direct rendering: DRI2 enabled
[    41.553] (II) intel(0): hardware support for Present enabled
[    41.553] (--) RandR disabled
[    41.556] (II) SELinux: Disabled on system
[    41.557] (EE) Failed to initialize GLX extension (Compatible NVIDIA X driver not found)
[    41.558] (II) intel(0): switch to mode 1366x768@60.0 on LVDS1 using pipe 0, position (0, 0), rotation normal, reflection none
[    41.558] (II) intel(0): Setting screen physical size to 361 x 203
[    41.582] (II) config/udev: Adding input device Power Button (/dev/input/event3)
[    41.582] (**) Power Button: Applying InputClass "evdev keyboard catchall"
[    41.582] (II) LoadModule: "evdev"
[    41.582] (II) Loading /usr/lib/xorg/modules/input/evdev_drv.so
[    41.582] (II) Module evdev: vendor="X.Org Foundation"
[    41.582]    compiled for 1.18.1, module version = 2.10.1
[    41.582]    Module class: X.Org XInput Driver
[    41.582]    ABI class: X.Org XInput driver, version 22.1
[    41.582] (II) Using input driver 'evdev' for 'Power Button'
[    41.582] (**) Power Button: always reports core events
[    41.582] (**) evdev: Power Button: Device: "/dev/input/event3"
[    41.582] (--) evdev: Power Button: Vendor 0 Product 0x1
[    41.583] (--) evdev: Power Button: Found keys
[    41.583] (II) evdev: Power Button: Configuring as keyboard
[    41.583] (**) Option "config_info" "udev:/sys/devices/LNXSYSTM:00/LNXPWRBN:00/input/input3/event3"
[    41.583] (II) XINPUT: Adding extended input device "Power Button" (type: KEYBOARD, id 6)
[    41.583] (**) Option "xkb_rules" "evdev"
[    41.583] (**) Option "xkb_model" "pc105"
[    41.583] (**) Option "xkb_layout" "sk"
[    41.583] (**) Option "xkb_variant" "qwerty"
[    41.596] (II) config/udev: Adding input device Video Bus (/dev/input/event6)
[    41.596] (**) Video Bus: Applying InputClass "evdev keyboard catchall"
[    41.596] (II) Using input driver 'evdev' for 'Video Bus'
[    41.596] (**) Video Bus: always reports core events
[    41.596] (**) evdev: Video Bus: Device: "/dev/input/event6"
[    41.596] (--) evdev: Video Bus: Vendor 0 Product 0x6
[    41.596] (--) evdev: Video Bus: Found keys
[    41.596] (II) evdev: Video Bus: Configuring as keyboard
[    41.596] (**) Option "config_info" "udev:/sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:01/input/input8/event6"
[    41.596] (II) XINPUT: Adding extended input device "Video Bus" (type: KEYBOARD, id 7)
[    41.596] (**) Option "xkb_rules" "evdev"
[    41.596] (**) Option "xkb_model" "pc105"
[    41.596] (**) Option "xkb_layout" "sk"
[    41.596] (**) Option "xkb_variant" "qwerty"
[    41.596] (II) config/udev: Adding input device Video Bus (/dev/input/event5)
[    41.596] (**) Video Bus: Applying InputClass "evdev keyboard catchall"
[    41.596] (II) Using input driver 'evdev' for 'Video Bus'
[    41.596] (**) Video Bus: always reports core events
[    41.596] (**) evdev: Video Bus: Device: "/dev/input/event5"
[    41.596] (--) evdev: Video Bus: Vendor 0 Product 0x6
[    41.596] (--) evdev: Video Bus: Found keys
[    41.596] (II) evdev: Video Bus: Configuring as keyboard
[    41.596] (**) Option "config_info" "udev:/sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:19/LNXVIDEO:00/input/input7/event5"
[    41.596] (II) XINPUT: Adding extended input device "Video Bus" (type: KEYBOARD, id 8)
[    41.596] (**) Option "xkb_rules" "evdev"
[    41.596] (**) Option "xkb_model" "pc105"
[    41.596] (**) Option "xkb_layout" "sk"
[    41.596] (**) Option "xkb_variant" "qwerty"
[    41.597] (II) config/udev: Adding input device Power Button (/dev/input/event1)
[    41.597] (**) Power Button: Applying InputClass "evdev keyboard catchall"
[    41.597] (II) Using input driver 'evdev' for 'Power Button'
[    41.597] (**) Power Button: always reports core events
[    41.597] (**) evdev: Power Button: Device: "/dev/input/event1"
[    41.597] (--) evdev: Power Button: Vendor 0 Product 0x1
[    41.597] (--) evdev: Power Button: Found keys
[    41.597] (II) evdev: Power Button: Configuring as keyboard
[    41.597] (**) Option "config_info" "udev:/sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0C:00/input/input1/event1"
[    41.597] (II) XINPUT: Adding extended input device "Power Button" (type: KEYBOARD, id 9)
[    41.597] (**) Option "xkb_rules" "evdev"
[    41.597] (**) Option "xkb_model" "pc105"
[    41.597] (**) Option "xkb_layout" "sk"
[    41.597] (**) Option "xkb_variant" "qwerty"
[    41.597] (II) config/udev: Adding input device Lid Switch (/dev/input/event0)
[    41.597] (II) No input driver specified, ignoring this device.
[    41.597] (II) This device may have been added with another device file.
[    41.598] (II) config/udev: Adding input device Sleep Button (/dev/input/event2)
[    41.598] (**) Sleep Button: Applying InputClass "evdev keyboard catchall"
[    41.598] (II) Using input driver 'evdev' for 'Sleep Button'
[    41.598] (**) Sleep Button: always reports core events
[    41.598] (**) evdev: Sleep Button: Device: "/dev/input/event2"
[    41.598] (--) evdev: Sleep Button: Vendor 0 Product 0x3
[    41.598] (--) evdev: Sleep Button: Found keys
[    41.598] (II) evdev: Sleep Button: Configuring as keyboard
[    41.598] (**) Option "config_info" "udev:/sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0E:00/input/input2/event2"
[    41.598] (II) XINPUT: Adding extended input device "Sleep Button" (type: KEYBOARD, id 10)
[    41.598] (**) Option "xkb_rules" "evdev"
[    41.598] (**) Option "xkb_model" "pc105"
[    41.598] (**) Option "xkb_layout" "sk"
[    41.598] (**) Option "xkb_variant" "qwerty"
[    41.598] (II) config/udev: Adding input device HID 04d9:1133 (/dev/input/event7)
[    41.598] (**) HID 04d9:1133: Applying InputClass "evdev pointer catchall"
[    41.598] (II) Using input driver 'evdev' for 'HID 04d9:1133'
[    41.598] (**) HID 04d9:1133: always reports core events
[    41.598] (**) evdev: HID 04d9:1133: Device: "/dev/input/event7"
[    41.652] (--) evdev: HID 04d9:1133: Vendor 0x4d9 Product 0x1133
[    41.652] (--) evdev: HID 04d9:1133: Found 3 mouse buttons
[    41.652] (--) evdev: HID 04d9:1133: Found scroll wheel(s)
[    41.652] (--) evdev: HID 04d9:1133: Found relative axes
[    41.652] (--) evdev: HID 04d9:1133: Found x and y relative axes
[    41.652] (II) evdev: HID 04d9:1133: Configuring as mouse
[    41.652] (II) evdev: HID 04d9:1133: Adding scrollwheel support
[    41.652] (**) evdev: HID 04d9:1133: YAxisMapping: buttons 4 and 5
[    41.652] (**) evdev: HID 04d9:1133: EmulateWheelButton: 4, EmulateWheelInertia: 10, EmulateWheelTimeout: 200
[    41.652] (**) Option "config_info" "udev:/sys/devices/pci0000:00/0000:00:14.0/usb3/3-2/3-2:1.0/0003:04D9:1133.0001/input/input9/event7"
[    41.652] (II) XINPUT: Adding extended input device "HID 04d9:1133" (type: MOUSE, id 11)
[    41.652] (II) evdev: HID 04d9:1133: initialized for relative axes.
[    41.652] (**) HID 04d9:1133: (accel) keeping acceleration scheme 1
[    41.652] (**) HID 04d9:1133: (accel) acceleration profile 0
[    41.652] (**) HID 04d9:1133: (accel) acceleration factor: 2.000
[    41.652] (**) HID 04d9:1133: (accel) acceleration threshold: 4
[    41.653] (II) config/udev: Adding input device HID 04d9:1133 (/dev/input/mouse0)
[    41.653] (II) No input driver specified, ignoring this device.
[    41.653] (II) This device may have been added with another device file.
[    41.653] (II) config/udev: Adding input device Laptop_Integrated_Webcam_HD (/dev/input/event10)
[    41.653] (**) Laptop_Integrated_Webcam_HD: Applying InputClass "evdev keyboard catchall"
[    41.653] (II) Using input driver 'evdev' for 'Laptop_Integrated_Webcam_HD'
[    41.653] (**) Laptop_Integrated_Webcam_HD: always reports core events
[    41.653] (**) evdev: Laptop_Integrated_Webcam_HD: Device: "/dev/input/event10"
[    41.653] (--) evdev: Laptop_Integrated_Webcam_HD: Vendor 0x1bcf Product 0x2982
[    41.653] (--) evdev: Laptop_Integrated_Webcam_HD: Found keys
[    41.653] (II) evdev: Laptop_Integrated_Webcam_HD: Configuring as keyboard
[    41.653] (**) Option "config_info" "udev:/sys/devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.5/1-1.5:1.0/input/input12/event10"
[    41.653] (II) XINPUT: Adding extended input device "Laptop_Integrated_Webcam_HD" (type: KEYBOARD, id 12)
[    41.653] (**) Option "xkb_rules" "evdev"
[    41.653] (**) Option "xkb_model" "pc105"
[    41.653] (**) Option "xkb_layout" "sk"
[    41.653] (**) Option "xkb_variant" "qwerty"
[    41.653] (II) config/udev: Adding input device HDA Intel PCH Mic (/dev/input/event12)
[    41.653] (II) No input driver specified, ignoring this device.
[    41.653] (II) This device may have been added with another device file.
[    41.654] (II) config/udev: Adding input device HDA Intel PCH Headphone (/dev/input/event13)
[    41.654] (II) No input driver specified, ignoring this device.
[    41.654] (II) This device may have been added with another device file.
[    41.654] (II) config/udev: Adding input device HDA Intel PCH HDMI/DP,pcm=3 (/dev/input/event14)
[    41.654] (II) No input driver specified, ignoring this device.
[    41.654] (II) This device may have been added with another device file.
[    41.654] (II) config/udev: Adding input device Atmel Atmel maXTouch Digitizer (/dev/input/event9)
[    41.654] (**) Atmel Atmel maXTouch Digitizer: Applying InputClass "evdev touchscreen catchall"
[    41.654] (II) Using input driver 'evdev' for 'Atmel Atmel maXTouch Digitizer'
[    41.654] (**) Atmel Atmel maXTouch Digitizer: always reports core events
[    41.654] (**) evdev: Atmel Atmel maXTouch Digitizer: Device: "/dev/input/event9"
[    41.709] (--) evdev: Atmel Atmel maXTouch Digitizer: Vendor 0x3eb Product 0x8803
[    41.709] (--) evdev: Atmel Atmel maXTouch Digitizer: Found absolute axes
[    41.709] (--) evdev: Atmel Atmel maXTouch Digitizer: Found absolute multitouch axes
[    41.709] (II) evdev: Atmel Atmel maXTouch Digitizer: No buttons found, faking one.
[    41.709] (--) evdev: Atmel Atmel maXTouch Digitizer: Found x and y absolute axes
[    41.709] (--) evdev: Atmel Atmel maXTouch Digitizer: Found absolute touchscreen
[    41.709] (II) evdev: Atmel Atmel maXTouch Digitizer: Configuring as touchscreen
[    41.709] (**) evdev: Atmel Atmel maXTouch Digitizer: YAxisMapping: buttons 4 and 5
[    41.709] (**) evdev: Atmel Atmel maXTouch Digitizer: EmulateWheelButton: 4, EmulateWheelInertia: 10, EmulateWheelTimeout: 200
[    41.709] (**) Option "config_info" "udev:/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5/2-1.5:1.0/0003:03EB:8803.0002/input/input10/event9"
[    41.709] (II) XINPUT: Adding extended input device "Atmel Atmel maXTouch Digitizer" (type: TOUCHSCREEN, id 13)
[    41.709] (II) evdev: Atmel Atmel maXTouch Digitizer: initialized for absolute axes.
[    41.709] (**) Atmel Atmel maXTouch Digitizer: (accel) keeping acceleration scheme 1
[    41.709] (**) Atmel Atmel maXTouch Digitizer: (accel) acceleration profile 0
[    41.709] (**) Atmel Atmel maXTouch Digitizer: (accel) acceleration factor: 2.000
[    41.709] (**) Atmel Atmel maXTouch Digitizer: (accel) acceleration threshold: 4
[    41.710] (II) config/udev: Adding input device Atmel Atmel maXTouch Digitizer (/dev/input/mouse2)
[    41.710] (II) No input driver specified, ignoring this device.
[    41.710] (II) This device may have been added with another device file.
[    41.710] (II) config/udev: Adding input device AT Translated Set 2 keyboard (/dev/input/event4)
[    41.710] (**) AT Translated Set 2 keyboard: Applying InputClass "evdev keyboard catchall"
[    41.710] (II) Using input driver 'evdev' for 'AT Translated Set 2 keyboard'
[    41.710] (**) AT Translated Set 2 keyboard: always reports core events
[    41.710] (**) evdev: AT Translated Set 2 keyboard: Device: "/dev/input/event4"
[    41.710] (--) evdev: AT Translated Set 2 keyboard: Vendor 0x1 Product 0x1
[    41.710] (--) evdev: AT Translated Set 2 keyboard: Found keys
[    41.710] (II) evdev: AT Translated Set 2 keyboard: Configuring as keyboard
[    41.710] (**) Option "config_info" "udev:/sys/devices/platform/i8042/serio0/input/input4/event4"
[    41.710] (II) XINPUT: Adding extended input device "AT Translated Set 2 keyboard" (type: KEYBOARD, id 14)
[    41.710] (**) Option "xkb_rules" "evdev"
[    41.710] (**) Option "xkb_model" "pc105"
[    41.710] (**) Option "xkb_layout" "sk"
[    41.710] (**) Option "xkb_variant" "qwerty"
[    41.710] (II) config/udev: Adding input device SynPS/2 Synaptics TouchPad (/dev/input/event8)
###/// A load of unrelated stuff about touchpad ///###
[    41.794] (**) Option "config_info" "udev:/sys/devices/virtual/input/input13/event11"
[    41.794] (II) XINPUT: Adding extended input device "Dell WMI hotkeys" (type: KEYBOARD, id 16)
[    41.794] (**) Option "xkb_rules" "evdev"
[    41.794] (**) Option "xkb_model" "pc105"
[    41.794] (**) Option "xkb_layout" "sk"
[    41.794] (**) Option "xkb_variant" "qwerty"
[    42.345] (II) intel(0): EDID vendor "CMN", prod id 5558
[    42.345] (II) intel(0): Printing DDC gathered Modelines:
[    42.345] (II) intel(0): Modeline "1366x768"x0.0   76.66  1366 1397 1462 1592  768 772 784 802 +hsync -vsync (48.2 kHz eP)
[    42.345] (II) intel(0): Modeline "1366x768"x0.0   51.01  1366 1380 1409 1592  768 770 777 800 +hsync -vsync (32.0 kHz e)

This is the xorg.conf.XXXXXXXX in use:

Section "ServerLayout"
    Identifier "layout"
    Screen 0 "nvidia"
    Inactive "intel"
EndSection

Section "Device"
    Identifier "intel"
    Driver "modesetting"
    BusID "PCI:0@0:2:0"
    Option "AccelMethod" "None"
EndSection

Section "Screen"
    Identifier "intel"
    Device "intel"
EndSection

Section "Device"
    Identifier "nvidia"
    Driver "nvidia"
    BusID "PCI:2@0:0:0"
    Option "ConstrainCursor" "off"
EndSection

Section "Screen"
    Identifier "nvidia"
    Device "nvidia"
    Option "AllowEmptyInitialConfiguration" "on"
    Option "IgnoreDisplayDevices" "CRT"
EndSection

For now, I am stuck with nouveau/intel, which is sometimes quite limiting. Any idea what can be going on? Maybe the missing /etc/X11/xorg.conf file could be the problem, but I don't know why it isn't there.

Note:
As of the main release of 16.04, the error has changed from no devices detected and no screens found to Failed to initialize GLX extension (Compatible NVIDIA X driver not found). Now, lightdm starts easier, but I still can't get past the login screen.

Further edit:
I had secure boot disabled all the time. I have installed bumblebee that added the nvidia driver (tried 304 and 340), but it was not able to start programs using the nVidia video card. Futher investigation has shown that modprobe for nvidia was failing due to something like this:

could not insert 'nvidia': Unknown symbol in module, or unknown parameter (see dmesg)

I tried a later version of the driver (361), but it kept on failing. I have read somewhere that i915 drivers were causing this trouble, but I had not them installed.

More information:
This appears to be the root cause. With nVidia driver installed together with its DKMS module, I could not insert it into kernel (using modprobe). The reported error was that it can't find it a specific PCI port (the one where it should be according to lspci). I haven't saved the exact wording, sorry for that.