I'd also recommend
JustLinux, where you'll find me lurking about. No sense in tying up an Amiga forum with FC4 questions.
BTW, have you tried running memtest86 from a shell (it's installed by default on your /boot partition)? And we'll need much more info from your lspci, lsmod, and dmesg outputs (post on the other forums, of course).
banzai
RH7-FC4
