Ever since I upgraded from 12.04 to 13.04, updates to Ubuntu Base does something to my nvidia drivers. I'm not sure what but when I log in I get the smallest resolution possible, no opengl, and no unity. X and kernel logs complain about not being able to load the driver due to a mismatch of versions between the X driver and kernel module. By uninstalling and reinstalling the drivers...
apt-get remove nvidia-310 && \ apt-get install nvidia-310
...and then rebooting, I get opengl and my original screen resolution back. Then I can run
ccsm and enable the opengl plugin and unity plugin.
So at least I have figured out a "fix" but it's a major pain as I have to do it after every Base update. How can I tell Ubuntu to leave my nvidia settings alone when updating?
As of this posting nvidia-310 is not the stable/recommended driver version. I upgraded them so I could use Steam. My guess is that this has something to do with it.