Rebooting???

[Apokalipse]

well a Thermaltake Volcano is a good fan i dont think overheating is a problem

it might even be something to do with your sound/video card or their drivers

 

[mrdinkel]

What 'bout that feature that will reboot your machine if it encounters a stop error... Might want to investigate the event log... useful information abounds from there...

 

[kboy]

I had a similar problem with my PC. After a year it started rebooting for no apparent reason. Swapped Ram, changed video drivers, checked Windows XP compatibility for all my hardware & software. Deleted tons of programs. System would stabilize but would start Re-booting again eventually. Couldn't run system maintenance, Virus scans etc...Finally I installed a CoolerMaster Aero 7 CPU Heatsink. It's been 3 months now without a crash. Hopefully I just didn't jinx myself. Worked for me so far. It could also maybe be your Power Supply. Try this link to check your power supply. It's a pretty cool calculator. Good Luck!!
www.jscustomerpcs.com/power_supply