Every now and then my computer restarts on its own. I have had the computer for 5 months and I still have not a reason. I have tried replacing harddrives and CD-drives and the keyboard. Im stumped.
-thanks

Random restarts is often the fault of the power supply, especially if it is running at or near it maximum power output.

When a computer starts the power supply first sends a small amount of current to the motherboard, just enough to power the North Bridge chip. At this time the North Bridge chips holds the reset signal to the CPU high. This prevents the CPU from doing anything till the power supply has stabilised. Once power has stabilised the power supply sends the full power to the motherboard and a power good signal to the motherboard which removes the reset signal to the CPU which then gets on with booting the computer. This usually takes just a few Milli seconds and prevents the CPU and memory form getting overloaded during the initial current surge during power on.

If during normal running of the computer the power supply gets overloaded and the voltage regulators are having problems keeping the voltages stable, the power good signal is removed which sends a reset signal to the CPU which then forces a re-boot.

On reboot the overload is removed which allows the computer to boot normally until the next overload.

But then it could also be faulty memory but faulty memory often results in a total seize up of the computer.

I would check the power supply first.

Post back your system specs and power supply wattage.

Stuart

Could be A LOT of different things, both software and/or hardware... which is why random restarts are tough to work out. Usually you are reduced to repair by trial and error.

I would start with the software because it doesn't cost anything to reload. Do a format and re-install the basic xp. run it for a couple of days. If the problem still exists then it's either xp conflicting with a piece of hardware or a pure hardware problem itself. If no problems then do a disk image, label it as "known to be good" and slowly reload each program alowing a couple of daye testing for each software load.