Mysterious shut down

[hobo_man]

Not really sure if this is a software problem or hardware, but a certain event made me think it's hardware. While I was on the computer, all I was doing was talking on MSN, my computer shut down with no apparent reason. Not only that..after, I couldn't turn my computer on by pushing the On switch. I actually had to unplug the computer from the power supply and then back in.
Is this a common problem? What could have caused this? Is it something that's serious?
Thanks.

 

[Athlon]

Hmmm, your processor might not be getting enough ventilation. I beleive that your computer will shut down if the processor gets too hot... but im not sure if that's your problem. If it is, then check to see if the inside of your PC has loads of dust inside that needs cleaning out. If it's clogged with dust then it will affect the air ventilation throughout your PC

 

[FlashDude]

I think its time you upgraded your powersupply, A bad mobo will do the same thing.

 

[MrCoffee]

Its almost certainly hardware related, monitor your processor and system temp to see if thats causeing the shutdown. Otherwise it may well be a power issue i.e. pad/insufficient PSU.