After playing around with my drivers, my Nouveau driver no longer seems to support 3D acceleration: Compiz effects are gone, as are 3D gaming capabilities.
Nouveau is still doing something correctly in 2D (e.g. the 1600x900 resolution is still correct, as compared to no NVIDIA driver at all, when it's 1280x768 instead).
How do I fix this without reinstall Ubuntu for the billionth time?
xorg.conf's that I've tried:
(empty)
This (which was the original):
Section "Device" Identifier "Default Device" Driver "nouveau" EndSection
Other things I've tried:
modprobe nouveausudo apt-get purge xserver-xorg-video-nouveau --removesudo apt-get install xserver-xorg-video-nouveau --reinstallUninstalling/reinstalling through Additional Drivers

ls -al /etc/alternatives/gl_conf. 3. Do you have a file callednvidia-installer-disable-nouveau.conf(or similar) in/etc/modprobe.d? 4. Are nvidia or nouveau in the output of`lsmod` after a boot? – htorque Aug 2 '11 at 7:56lrwxrwxrwx 1 root root 24 2011-08-01 23:52 /etc/alternatives/gl_conf -> /usr/lib/mesa/ld.so.conf. 3. No, I've removed that when uninstalling the proprietary driver. (nouveau does start, it's just that I don't get 3D acceleration anymore, just 2D graphics). 4. Yes, there are 5 entries that matchnouveau. 5. No. 6. No. This thing was fine like 20 minutes before I fiddled around with the drivers, I didn't add/remove anything else during that time :) – Mehrdad Aug 2 '11 at 11:36