Re: OpenGL problem 9746 driver
UPDATE: for those experiencing this problem, add
Option "DamageEvents" "false"
...to your xorg.conf and see if the problem doesn't go away.
Disabling DamageEvents has worked for me; GLX is now working with Composite enabled although the output stutters and Xorg uses a lot more CPU.
I've compiled a GENERIC kernel and will reboot using that shortly to see if that makes any difference.