athlon overheating?

Athlon XP2200 freezes after a few hours use with kernel panic on reboot until (presumably) it's cooled down enough. I have the packman sensors rpm installed with 9.1 and am using gkrellm to monitor the sensors. The temp1 and temp2 sensors are working well I think, fluctuating between 35º and 55º but I can't get the fan sensors to show anything other than zero. Could anyone with an AMD give me reasonable working values for the temp1 and temp2 sensors? And/or how to monitor the fans correctly? Or must I move to Intel? Cheers, Steve.