Computer randomly shutting down

My son has just installed a new HD, running XP Pro. It's the 2nd HD he has had to replace in 2 months They just kept getting bad sectors and would not let him access his files, and then finally wouldn't boot at all.

So, I've been loading his new HD up with Avast, Zonealarm, Emco, Spybot S&D, SpywareGuard, SpywareBlaster, CrapCleaner and Firefox - usual stuff.

Part way through the S&D update the PC just shut down. It was also doing the Windows SP2 update at the time, so I just put it down to being antsty Rebooted, let SP complete, then ran S&D. Again it auto-shutdown..no blue screen, nothing...just shut down like a power cut.

So uninstalled S&D incase corrupt; running Avast AV and it does it again...shutdown like a power cut. So I'm thinking it's not the software after all. After pressing the power button a few times and holding it in,it boots up just fine again, as if nothing had happened.

Could it be the power supply is dodgy....could this also have resulted in 2 HD burnouts? If not, any suggestions guys?

All help greatly appreciated, thanks

 

I would say one of two possibilitys, the power supply like you think, or over heating. The power supply should have damaged maybe the cd-rom or anything that is connected to that line. Keep an eye on temps and voltage's.

http://www.majorgeeks.com/SpeedFan_d337.html

 

Thank you...will do....thanks for the link, very helpful