computer shuts down occasionally by itself

Hi,

The two most likely culprits are overheating of the CPU or some infection.

To check the heat problem remove the computer case cover and look at the CPU heat sink, and the rest of the computer. If it is full of dust / fluff then remove it, with compressed air. Don't forget to blow out the power supply too.If you don't have compressed air available, then a small brush and vacuum cleaner are the next best thing.
A word of warning - if you use air then physically prevent the fan(s) from rotating, as they can become generators and damage your mobo etc.

An infection, run updated anti virus, anti spyware programs.

Herb

overheating :) clean the heatsink and fan out........

i had this trouble in summer when it was hot even with a clean fan, solved the problem byu taking the side of the case :)

install and check out the temperatures, if you minimise it will overlay temps in the top right hand corner of your screen.

You can check out temps, fan speed etc also.