Atlon XP +2100

If you have less than a 300 Watt power supply, then yes, it is your power supply.

Depending on your system configuration, I would step up to a 400 or 500 watt supply.

If you have several fans, 2 CD drives, 512MB or more of RAM, and a high power video card, then you need more than the base 300 Watt supply.

I have seen some 350 Watt supplies with lower current ratings than the 300 Watt supplies I use.

Other hardware, or even Windows itself may be the root cause.

Please try and detail more information on what is happening, and when the system re-boots.

Chas

I had the same problem with my Athlon XP 1600, complicated by recurring application crashes. Ultimately, the problem was traced to a chipped proc - damaged from improper heatsink placement.

I assumed this was a power supply or motherboard issue, but a new CPU did the trick. Remember that Athlon XP cores can get easily broken during heatsink installation.