Ubuntu blank screen after login

Ubuntu

I have a laptop running Ubuntu 13.10. It was running fine till yesterday when I installed OpenCV 2.4 using Synaptic (if that is of any relevance since there is no other change in configuration). This morning, I powered it on and it comes to the screen asking for login, even showing my background correctly. However, after I login, the screen goes blank. I can see the mouse cursor and it moves when I use the trackpad, but I am unable to do anything else. I am not able to start terminal window or anything else because I do not have any icon. From the login screen, I tried to change to Gnome (instead of Ubuntu default) but still, had no luck. Can someone please help?

There should be a command to go into non-GUI mode but I cannot recall that either.

The output from lspci | grep VGA is

00:02.0 VGA compatible controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (primart) (rev 0c)

Looks like it is unable to load Plugin opengl which must be because of my install of OpenCV.

apt-cache policy nvidia

nvidia:
  Installed: (none)
  Candidate: (none)
  Version table:

apt-cache policy fglrx

fglrx:
  Installed: (none)
  Candidate: 2:13.101-0ubuntu3
  Version table:
     2:13.101-0ubuntu3 0
        500 http://us.archive.ubuntu.com/ubuntu/ saucy/restricted amd64 Packages

If it is of any help, I typed the command glxinfo and got the error:

Xlib:  extension "GLX" missing on display ":0".
Error: couldn't find RGB GLX visual or fbconfig

Best Answer

After examining your Xorg.0.log, it appears that Xorg is attempting to load the glx module with the nvidia drivers, and since you don't have an Nvidia card it's failing to load. Removing the Nvidia packages should solve your issue: 

sudo apt-get purge nvidia-common nvidia-settings-319-updates nvidia-319-updates

Then restart.

In case you're interested, here are the important lines in your Xorg.0.log: 

[    26.590] (II) "glx" will be loaded by default.  
...  
[    30.675] (II) LoadModule: "glx"
[    30.675] (II) Loading /usr/lib/x86_64-linux-gnu/xorg/extra-modules/libglx.so
[    31.137] (II) Module glx: vendor="NVIDIA Corporation"
[    31.137]    compiled for 4.0.2, module version = 1.0.0
[    31.137]    Module class: X.Org Server Extension
[    31.137] (II) NVIDIA GLX Module  319.60  Wed Sep 25 14:24:11 PDT 2013
[    31.138] Loading extension GLX  
...  
[    31.250] (EE) Failed to initialize GLX extension (Compatible NVIDIA X driver not found)

This Ubuntu Forums thread was very useful in figuring this out.

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