Ubuntu – (13.04) lightdm crashing – black screen flashing cursor

I am using the 13.04 x64 release of Ubuntu on my PC and at least it works so far as it should. But suddenly the lightdm crashes during boot and even if I try to start it manually from terminal after switching to another tty.

I don't know what may cause the problems because I didn't even install any graphics-drivers for my nvidia card (because I just know those problems since years and skip those problems by not installing any of them).

It worked fine for some days after fresh install and updates, but now it just does not what it should.

Switching to gdm did solve the problem logging in to my computer with a gui but hell this lightdm should work I guess..

The logs aren't pretty much of help for me but maybe someone know what's up?

lightdm.log

 [+0.00s] DEBUG: Logging to /var/log/lightdm/lightdm.log [+0.00s]
 DEBUG: Starting Light Display Manager 1.6.0, UID=0 PID=7369 [+0.00s]
 DEBUG: Loaded configuration from /etc/lightdm/lightdm.conf [+0.00s]
 DEBUG: Using D-Bus name org.freedesktop.DisplayManager [+0.00s] DEBUG:
 Registered seat module xlocal [+0.00s] DEBUG: Registered seat module
 xremote [+0.00s] DEBUG: Adding default seat [+0.00s] DEBUG: Starting
 seat [+0.00s] DEBUG: Starting new display for greeter [+0.00s] DEBUG:
 Starting local X display [+0.00s] DEBUG: Using VT 7 [+0.00s] DEBUG:
 Activating VT 7 [+0.01s] DEBUG: Logging to /var/log/lightdm/x-1.log
 [+0.01s] DEBUG: Writing X server authority to /var/run/lightdm/root/:1
 [+0.01s] DEBUG: Launching X Server [+0.01s] DEBUG: Launching process
 7376: /usr/bin/X :1 -core -auth /var/run/lightdm/root/:1 -nolisten tcp
 vt7 -novtswitch [+0.01s] DEBUG: Waiting for ready signal from X server
 :1 [+0.01s] DEBUG: Acquired bus name org.freedesktop.DisplayManager
 [+0.01s] DEBUG: Registering seat with bus path
 /org/freedesktop/DisplayManager/Seat0 [+0.61s] DEBUG: Got signal 10
 from process 7376 [+0.61s] DEBUG: Got signal from X server :1 [+0.61s]
 DEBUG: Connecting to XServer :1 [+0.61s] DEBUG: Starting greeter
 [+0.62s] DEBUG: Started session 7385 with service 'lightdm-greeter',
 username 'lightdm' [+0.64s] DEBUG: Session 7385 authentication
 complete with return value 0: Success [+0.64s] DEBUG: Greeter
 authorized [+0.64s] DEBUG: Logging to /var/log/lightdm/x-1-greeter.log
 [+0.64s] DEBUG: Session 7385 running command
 /usr/lib/lightdm/lightdm-greeter-session /usr/sbin/unity-greeter
 [+0.68s] DEBUG: Greeter closed communication channel [+0.68s] DEBUG:
 Session 7385 exited with return value 1 [+0.68s] DEBUG: Greeter quit
 [+0.68s] DEBUG: Failed to start greeter [+0.68s] DEBUG: Stopping
 display [+0.68s] DEBUG: Sending signal 15 to process 7376 [+0.82s]
 DEBUG: Process 7376 exited with return value 0 [+0.82s] DEBUG: X
 server stopped [+0.82s] DEBUG: Removing X server authority
 /var/run/lightdm/root/:1 [+0.82s] DEBUG: Releasing VT 7 [+0.82s]
 DEBUG: Display server stopped [+0.82s] DEBUG: Stopping seat, failed to
 start a display [+0.82s] DEBUG: Stopping seat [+0.82s] DEBUG: Seat
 stopped [+0.82s] DEBUG: Required seat has stopped [+0.82s] DEBUG:
 Stopping display manager [+0.82s] DEBUG: Display manager stopped
 [+0.82s] DEBUG: Stopping daemon [+0.82s] DEBUG: Exiting with return
 value 1

---

x-0-greeter.log

 Error writing X authority: Failed to write X authority
 /var/lib/lightdm/.Xauthority: Success

---

x-1-greeter.log

 Error writing X authority: Failed to write X authority
 /var/lib/lightdm/.Xauthority: Success /var/log/lightdm/x-1-greeter.log
 (END)

---

x0.log

 X.Org X Server 1.13.3 Release Date: 2013-03-07 X Protocol Version 11,
 Revision 0 Build Operating System: Linux 3.2.0-37-generic x86_64
 Ubuntu Current Operating System: Linux stefan-dev 3.8.0-30-generic
 #44-Ubuntu SMP Thu Aug 22 20:52:24 UTC 2013 x86_64 Kernel command line: BOOT_IMAGE=/boot/vmlinuz-3.8.0-30-generic
 root=UUID=6e9c6967-a55f-49b8-b690-7257b359ae8d ro quiet splash
 vt.handoff=7 Build Date: 17 April 2013  10:43:13PM xorg-server
 2:1.13.3-0ubuntu6 (For technical support please see
 http://www.ubuntu.com/support)  Current version of pixman: 0.28.2
Before reporting problems, check http://wiki.x.org
to make sure that you have the latest version. Markers: (--) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown. (==) Log file: "/var/log/Xorg.0.log", Time: Tue Sep 17 18:27:30 2013
 (==) Using system config directory "/usr/share/X11/xorg.conf.d"
 Initializing built-in extension Generic Event Extension Initializing
 built-in extension SHAPE Initializing built-in extension MIT-SHM
 Initializing built-in extension XInputExtension Initializing built-in
 extension XTEST Initializing built-in extension BIG-REQUESTS
 Initializing built-in extension SYNC Initializing built-in extension
 XKEYBOARD Initializing built-in extension XC-MISC Initializing
 built-in extension SECURITY Initializing built-in extension XINERAMA
 Initializing built-in extension XFIXES Initializing built-in extension
 RENDER Initializing built-in extension RANDR Initializing built-in
 extension COMPOSITE Initializing built-in extension DAMAGE
 Initializing built-in extension MIT-SCREEN-SAVER Initializing built-in
 extension DOUBLE-BUFFER Initializing built-in extension RECORD
 Initializing built-in extension DPMS Initializing built-in extension
 X-Resource Initializing built-in extension XVideo Initializing
 built-in extension XVideo-MotionCompensation Initializing built-in
 extension SELinux Initializing built-in extension
 XFree86-VidModeExtension Initializing built-in extension XFree86-DGA
 Initializing built-in extension XFree86-DRI Initializing built-in
 extension DRI2 Loading extension GLX resize called 1680 1050 Server
 terminated successfully (0). Closing log file.