Comment 20 for bug 15178

This bug is solved for me:
William Anderson showed me the way here:

http://bugzilla.ubuntu.com/show_bug.cgi?id=8861#c20

I can't find AGPFastWrite in the BIOS so I put:
Option "AGPFastWrite" "0"
in my xorg.conf

And it works now: no lockup on the websites where I freezed every time!!

Many many thanks because I spent many hours to solve my freezes...

:-D