Hello,
Sad to hear about your troublesome computer.
My bet is that it's cooling related. I have an 1GHz Athlon, which was delivered with an ThermalTake Chrome Orb. It did not run stable, and the temperature was around 56C.
A ThermalTake Chrome SuperOrb (two fan monster, very noisy) brings the temperature on my system down to around 54C. That solved the problem.
Your 300W AMD-approved PSU is what I'd be looking at next. There might be a sticker on it stating that it's approved, but that doesn't mean it is. Generally the larger and more expensive powersupply you get, the more happy you'll be :) You can always move the powersupply to your next computer when that time comes.
If you have SCSI-harddrives, lots of CD-ROMs, a GeForce2 or just a power-hungry system, that will also demand a better PSU. The PSU can also have taken damage if it has been overloaded for a longer period. Most PSUs will run at 130% capacity for a longer time, but will either fail completely or just degrade.
Hope this helps.
Lars
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Lars
MkII 40gig 090000598