Ubuntu :: Freezing At Login Screen?

Diagnosis: I'm running Ubuntun 10.04. It has been running smoothly for pleny of time (8~9 months). I've done the clean install (not upgrading).

One day I left the screen locked and when I returned it was frozen. I restarted and it froze in the login screen (sometimes when I restart it actually log in my account, but freezes right after some minutes). The mouse pointer still moves.

I still can log in remotely through SSH, even though the system is frozen. So I suspect it has to do with the GUI.

Here's the output of my /var/log/Xorg.0.log

I think the error started in here:

Code:
(WW) Jan 21 11:29:46 NVIDIA(0): WAIT
(2, 6, 0x8000, 0x00007b6c, 0x0000aa04)

[Code]....