I haven't heard of any AMD based machine having this problem before but the symptoms are identical to what I got. For me the only thing that seems to help is booting with a kernel without SMP support. Check these threads:
http://www.knoppix.net/forum/viewtopic.php?t=6154
and
http://www.knoppix.net/forum/viewtopic.php?t=8053
(the later indicates it might be possible to fix it by replacing the BIOS, which for one guy got the latest version working with the nosmp cheat code)