One thing you could try: edit your /etc/X11/xorg.conf file, and change:
---- to ----
This, unfortunately, will disable video acceleration, but at least we will know if nvidia drivers are the problem.
Gigabyte GA-P35-DS3L - Intel(R) Core(TM)2 Duo CPU E6750@ 2.66GHz
nVidia GeForce 7600 GS
2 GB RAM