i don't use these but have been following the banter
both RENDER and COMPOSITE extensions in xorg appear to be unstable or unsupported fully by nvidia yet or something.
try this and then enable stuff slowly from here
composite and GLX canot coexist without AllowGLXWithComposite
but better to leave composite off altogether
Code:
Section "Extensions"
Option "Composite" "Disable"
Option "RENDER" "Disable"
EndSection
Section "Device"
Section "Device"
Identifier "Videocard0"
Driver "nvidia"
VendorName "Videocard vendor"
BoardName "NVIDIA GeForce 4 MX (generic)"
Option "RenderAccel" "false"
Option "AllowGLXWithComposite" "false"
End Section