Computer Shut Down Issue

Okay, so I've did some further investigation to know why my PC shuts down when I'm playing games. There's two possible reasons:
1) Overheat
2) Virus

My PC shuts down on the following games:

1) A.V.A. - After 2 and a half games.
2) Genesis AD - After 3 or 4 games.
3) SPORE™ - After 3 ~ 4 hours.

But the other day I installed Left 4 Dead 2 on my PC and I played Multiplayer games non-stop. My PC didn't shut down at all. I've played, the other day, for 5 hours. (Around that.)

Sure, it may be overheat, 'cause I bet I could fry some eggs. The screen and the heatsync areas are burning hot. I don't know why it's burning hot on my screen area, since i connected my laptop to a old's PC screen and the Laptop's screen doesn't show anything currently. (That's what happens when you throw a small light mobile phone to your Laptop's screen, without any strength at all. And... crash.)

I don't know if it's Virus 'cause I scanned my PC, like, 4 times already and all I got is password protected files that couldn't be scanned. Like Garena files and so on. My avast! randomly detected a GameGuard's virus and the recommended action was to ignore. Someone told me that it was a rootkit to improve GameGuard's.... blah, blah. I deleted it anyway.

My PC started shutting down, like, in the start of April. Any advises?

You r obsessed!......Anyways, yea u need to give your computer a break sometimes. My computer crashed cause i played so much once.

The rookit should not be ignored look at this post:

http://www.mpgh.net/forum/201-ava-ha...le-urgent.html

LOL but you use for like 4 hours straight

DO u have enough money for another computer or laptop

Oh well..... i dont know
do u have an Xbox or ps3

OH lol well do u have games for the psp

I know i have one too
but you can dowload games to your PSP.....
how big is your memorycard for your PSP

hmm..... how did u get 2gb memory card
btw how did u get animated avatar