I have been facing a curious and very annoying issue from the time when I updated to Ubuntu Maverick. When I am watching some video – especially in a media player like Totem or VLC, the screen will suddenly freeze. The screen will not update but I was able to listen to audio. Similarly, I was also able to use the keyboard. For eg, if I pressed spacebar, the video paused. This issue was very annoying as it kill all the fun in watching the video🙂
I tried lot of debugging to no avail. One good resource I found in the process is the X freeze trouble shooting wiki. While it contained lot of very interesting information, none of it really solved my problem. One of the interesting point that was mentioned in the Wiki was that there are multiple possible ways to cause a screen freeze and it need not be an X issue at all. So I checked all my other display components like Compiz, Docky etc systematically.
The culprit seems to be the Nvidia drivers that I was using. This kind of surprised me as I have been using them for almost 2 years without any issue. My guess is this : One of the recent changes in Maverick was to make nouveau driver as the default one. I remember doing something to disable the driver in 10.04 but did not do the same in 10.10 . "Probably" both the drivers interfered with each other and caused this issue.
Anyway, the solution that fixed my issue was simple – Goto System -> Administration -> Additional Drivers. The dialog will show all the external display drivers available. Select the installed driver and uninstall it. When you reboot, Ubuntu will automatically select the nouveau driver and all will be fine.
I should mention one another thing : I was using Nvidia’s beta driver instead of the normal drivers. I did try removing the beta drivers and using the regular one. The problem still persisted. Removing both the drivers finally fixed the issue.
But my problems were not fully solved by using nouveau driver. I got a new issue. Sometimes randomly my screen will become garbled – For eg if I open some dialog and used some of its control, then these controls will linger even after closing the dialog. So what will happen is that my screen will have few zombie controls which will hide the actual UI that was supposed to be displaying. Interestingly, the fix for this was simple.
I completely removed the following compiz related packages – compiz, compiz-gnome and compiz-core. I used the purge command instead of just the remove. Once I rebooted the machine the issue seems to have gone.
This may or may not be the correct fix for your screen freeze issue but I am writing it in the hope that it might be useful for some one🙂