Computer shutting off gaming

alright well i got my computer about 2 months ago and about a week ago i started haveing a problum with my computer shutting down randomly when i start playing a online game with decent graphics and i got no clue why its doing this so does anyone have a solution?

My system specs include

windows os: vista
processor: Intel(R) Core(TM)2 quad CPU 2.55GHz
memory: 8190MB RAM
graphics card: ATI Radeon HD 4650

again if anyone has any clue that would be awesome
 
I suggest doing the following...

1. Download Driver Cleaner Pro or Driver Sweeper (both have free versions; make sure the version will work with your OS) to your desktop screen and install.

2. Download the latest diver(s) for your video card but don't install them.

3. Uninstall your video card drivers and reboot your PC into Safe Mode. Run Driver Cleaner Pro or Driver Sweeper but ONLY for the video card drivers. I had someone use it on their chipset drivers! If it doesn't find any video card drivers that is quite okay; leave all other drivers alone.

4. Reboot and install new video card drivers.

* Get back to us with the results.

Question: Does this issue occur when playing games offline?
 
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