try mem=nopentium at boot
I have read that some AMD's have broken AGP.
If you use lilo, you need to append mem=nopentium in /etc/lilo.conf
or if you use grug, in /etc/grub.conf
if you edit your file, you will find "append ide-scsi=hdx"...
in lilo. put mem=nopentium after
I think, you can pass a command to try, in lilo
press esc, and then type linux mem=nopentium
or ir grub, editing line (e) , select line (e), add mem=nopentium(enter) and press b.
If this works, is a hardware bug.