You can try that - simply create the xorg.conf with those contents, but leave out some of the extra options, i.e.
Option "Shadow" "true"
I think enabling the shadowfb was a workaround of some kind - not sure if it's still needed now possibly still is in squeeze.
Original thread: http://forums.debian.net/viewtopic.p...=63662#p375172
But first post the output of
grep EE /var/log/Xorg.0.log
grep WW /var/log/Xorg.0.log
I assume that you're running squeeze?