System hardlocks and reboots

Question

Hi,
I've recently been getting hardlocks followed by my system rebooting.
This 'mostly' happens, only when I use compiz, especially when browsing the web with firefox(shiretoko) on more 'demanding' sites(performance wise).
However it has also has happened when just browsing my files with nautilus or checking my torrents with transmission, but with compiz active.
Apart from that, I've noticed the same thing happening, when using metacity + firefox and loading big (2000x1500) images on a site like imageshak.
I'm running gnome 2.28, enabled testing and use xf86-video-ati. KMS is enabled early, directrendering works (as does compiz..).
I've gone through my logs but never seem to find anything...
Any ideas to what could be causing this?
Could this be a hardware-error with my gpu (radeon 9800)? I should mention that under 'extreme load' (newer games on windows) my system also chickens out, but normal desktop usage shouldn't fall into that category..

Answer 1

Hmm, I've checked dmesg, nothing like those warnings you mentioned...
My System is properly configured, it has been running since 2005, and that usually quite stable. As mentioned above, only under 'extreme load'  it sometimes dies, but I'm very certain that this is related to a fault with the gpu, as I've noticed this only happening when for instance using 'ultra quality' in doom3 (in windows), or more generally when using the 'highest' texture-detail setting in games.
I think that somehow 'compiz' (or whatever part it uses in the ati-driver) is triggering that same behaviour, but obviously I'm not sure.
Is compiz + xf86-video-ati unstable for more people? Or is it just my quirky hardware?