I'm not sure what is wrong with the computer.. could be overheated since its been on for a long time. I'm not sure if its any virus causing this, but heres my problem

my brothers computer shuts down every 5 minutes to an hour longest after its open. could the problem just be overheating? the computer wont stay open long enough for me to download and run hijack this.

A good first step is to clean the computer.

Some guides here:

http://www.google.com/search?sourcei...clean+computer

Just to clarify: I was referring to the links regarding physically cleaning inside the case: not software cleaning.

what could i do now? is the cpu damaged?

I was suggesting opening the computer and cleaning out the dirt/dust etc.

The Google I posted offers several tutorials on how to do this.

i just cleaned out most of the dust

Ok. See if it makes any difference when you run it.