Fedora Core 2 freeze after several minutes/hours

[e98cuenc free fr]

Hi!

I'm running FC2 on a PIII 733Mhz with a Powercolor graphic card (powered by an
ATI 7500).

After a few (1-2) hours of use, it stops dead for no obvious reason (doing
nothing CPU intensive, sometimes just reading a local html page with mozilla).

Everything is freezed, including the mouse. I've reproduced the same problem
with another card (a nvidia GeForce 2).

It doesn't seems to happen when I don't run X (that's why I suspected the
graphic card...), but I have still not remained for hours on without X, so I
don't know for sure.

Does anybody have any hints about what can I try to get some info about this
freeze?

Cheers,