Comment 29 for bug 9713

I was having exactly the same problems, AMD64 ATI 9200, random crashes in
firefox etc.

Solution was to install fglrx drivers and change xorg.conf to point to fglrx
instead of ati

driver:"ati"

look at

http://www.ubuntuforums.org/showthread.php?t=22496&highlight=ATi+crash
http://www.ubuntuforums.org/showthread.php?t=20191&highlight=amd64+fglrx for
more info

one note - the fglrx driver wont output via DVI, so you will have to plug your
monitor into the analogue output of your video card to get a display
http://www.ubuntuforums.org/showthread.php?t=21927&highlight=fglrx+blank+screen