most likely "composite" extersion is the problem
you can use either Composite or OpenGL overlays, but not both.
try
Option "AllowGLXWithComposite" "true"
and if that won't work try
Option "Composite" "false"
and/or
Code:
Section "Extensions"
Option "Composite" "Disable"
EndSection
or
Code:
Section "Extensions"
Option "Composite" "false"
EndSection