Friends: I am running a Pentium 4 1.8GHz system with 512 MB of RAM, Windows XP SP2. The computer seems to be shutting down without warning whenever I try to run virus scans, defragging or system file checker. The virus scans run OK in safe mode. The cooling fans are clean and run OK. When the computer shuts down, the power light on the tower case and the num lock light on the keyboard stays on and the computer would not re-boot from the main power button. I have to remove all power from the mains for 10 seconds, re-insert the power cord then re-boot. Event viewer provides no clues. Any ideas how to fix this? Thanks.

Hello Wakenaam

Welcome back to PCHF

Mmmm it is a bit of an enigma is it not, my suggestion would be a failing/faulty psu, but if you would kindly wait for the Tech team to arrive shortly, I'm sure they will be able to help you.

Have you added any new hardware lately or any high-resources software?

I would say it is probably the PSU or overheating problem, but we cant tell yet.