dust can cause short circuits. Vacuum out the inside to keep it clean. check your power source. Do you have heavy machinery attached to the same circuit? e.g. kettle? TV? etc., Starting those machines together can draw enough power to upset your computer.
I'm pretty sure it isn't overheating. It happens sometimes while the system is booting the first time, so there isn't really any way that it could be overheating that fast. Also the diagnostic says the CPU is only at about 35*. IT guy at work suggested that I check the BIOS setting for the auto restart on bluescreen error. After that, I'll have to check the memory first and then the hard disk. The odd thing is that it isn't really giving me an error to look into.
Initially it would only happen while running my brokers desktop java platform. Now it happens during a simple screensaver.
When in doubt reformat and install Windows again, that way you completely rule out software if it is still happening and can concentrate on hardware
Restart on a blue screen (system crash) isnt a BIOS function, its a Windows setting: Control panel->System->Advanced tab->Startup and Recovery (Settings)->System Failure->Automatically Restart (Checkbox) Your BIOS likely has a setting that allows you to decide if the PC should remain off or restart automatically after a power failure I would check the Windows event log to see if there are any strange messages that coincide with the restarts. If it sometimes tells you to check the hard disk that means that it did not shutdown gracefully (which would rule out Windows restarting itself for an OS patch) - I would follow the suggestions for others about checking into hardware problems. Unless the PC is fairly new, you may be better off just getting a new one.
\ PC is only about 1 1/2 years old. Generally no message comes up at all and there is no reference to anything in the error log. One time there was about a 2 second message on the screen when it rebooted that said I might need to scan my hard disk.
Yes. Sounds like you have malware, virus, or just general buildup of schmutz and corruption. Now is the time to try "registry fixers" or "system repair" software, but be prepared to make a copy of your important stuff and do a fresh install of the OS.
Another option: do a fresh OS install in another partition (or another drive if you have a spare one). Leave the fresh OS running for a while, if the spontaneous reboot happens with the new OS then it probably is a hardware problem, if not then its probably a software problem in the old OS partition.