Weird, it really sounded like a overheating or memory issue.
I didn't mean it was a hard task, it's just going to push your computer more than just when you are say browsing the internet. My last PC, everything seemed fine doing basic stuff but when I went to launch a game the screen would get distorted and the game eventually crash. I thought it was a video card issue for a while until I tested the memory and found out one of my memory sticks was busted. It only became a visible when I was running processes that used up enough memory for the computer to start using that stick of memory intensively.
At this point you need to narrow down where it's breaking. Since heat isn't the issue, there could be a hardware issue. There could be an issue with your motherboard, power supply, or video card. You could disable the vid card and try running on integrated graphics and see if it still freezes. The other two are harder to test. You could also try reinstalling Windows (or do a refresh if you're using Windows 8). If you can't determine the issue you may need to contact the manufacture, or take it to a technician.