I'm having a similar bug with the radeon driver. Randomly (though often when watching youtube) the screen would just stop updating. I could move the mouse cursor around and I think it was accepting keyboard input but nothing on the screen updated. I could ctrl-alt-f1 over and kill the x session and everything would be fine for awhile again.
However, for me it just started happening which led me to test if it was related to recent kernel upgrades. I rebooted with 3.2.0-23 and now I don't seem to have this bug! I did not test 3.2.0-24, but I definitely see the bug with 3.2.0-25. linux-image-generic-pae: Installed: 3.2.0.25.27 Candidate: 3.2.0.25.27 Version table: *** 3.2.0.25.27 0 500 http://us.archive.ubuntu.com/ubuntu/ precise-proposed/main i386 Packages 100 /var/lib/dpkg/status 3.2.0.24.26 0 500 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main i386 Packages 500 http://security.ubuntu.com/ubuntu/ precise-security/main i386 Packages 3.2.0.23.25 0 500 http://us.archive.ubuntu.com/ubuntu/ precise/main i386 Packages -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-nouveau in Ubuntu. https://bugs.launchpad.net/bugs/994203 Title: Xorg freeze with Nouveau drivers To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-nouveau/+bug/994203/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp