Hi, my PC is a Pentium 4 2.0A GHz with 256MB ram, etc. Lately, the PC keeps restarting for no reason. It keeps restarting at the POST screen, or even when I'm in BIOS. If I am really lucky, I can get to the Windows XP desktop, only for it to restart. I have ruled out the HDD, as a faulty HDD won't be a culprit for restarts at the POST screen. I have changed the power supply and the power outlet to which the PC is plugged into.

I don't see any "swollen" or "bloated" capacitors on the motherboard, and I have replaced the RAM with a new stick. Sometimes when the PC restarts, the monitor doesn't detect anything, the USB mouse light will be 'ON' and the NUM lock light will be lighted and jammed for a long time. I suspect the culprit is the mobo, or the CPU itself. Any suggestions and advice will be much appreciated. Thank you!

have you checked to see if there is a BIOS update for you system. Many times BIOS issues just show up, after some triggering event happens on a computer.
could be.
Have you performed a virus scan? what virus software do you use? Is it up to date?

Hi, I use Avast Anti-virus, it has the latest virus definitions with updates, etc. And i did a thorough boot-scan, no viruses detected. My mobo is a MSI 845PE Max. I have yet to do any BIOS updates for it, but will do the updates now. Thanks for the tip!

Here is a little bit of info on how to reset the bios for that mobo. the site is: http://www.msicomputer.com/support/sup_tshoot.asp There is a lot of great info here.

Incorrect BIOS settings by user
-Clear CMOS with jumper JBAT1
With system powered off move jumper JBAT1 from pins 1-2 to pins 2-3 for 15 seconds and then return the jumper to pins 1-2 and retest the system.