Try to go to the console with "ctrl+alt+f1", edit the xorg.conf (change nv to nvidia), with ctrl+alt+f7 back to X, restart X with ctrl+alt+backspace and everything worked for me again
-- kubuntu livecd garbled screen https://launchpad.net/bugs/45665 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
