I'm having the same issue, it appeared not too long ago. Kubuntu 13.04 with xorg-edgers PPA. I'm using the nvidia-313 driver.
Linux user 3.8.0-2-generic #6-Ubuntu SMP Fri Jan 25 22:03:57 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-intel in Ubuntu. https://bugs.launchpad.net/bugs/993187 Title: ubuntu 12.04 completely freezes frequently. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/993187/+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