If you have the nvidia proprietary drivers installed add this or verify that you have on /etc/X11/xorg.conf:
Code:
Section “Module”
Load “glx”
Load “extmod”
EndSection
Section “Device”
Identifier “Videocard0″
Driver “nvidia”
Option “AddARGBGLXVisuals” “True”
Option “DisableGLXRootClipping” “True”
EndSection
Section “DRI”
Group 0
Mode 0666
EndSection
You can enable the effects on System->Preferences->Desktop Effects of the gnome menu.