Quote Originally Posted by Danimal View Post
It sounds like your graphics processor is failing. First thing that I would do is pull the whole thing apart, blow all the dust off of everything and then clean and re-apply thermal paste on the heat sinks for the cooler. Depending on the age of the computer, the processor and the configuration of the mother board there are a lot of different things that could be going wrong with it. Thermal paste is like $1 and available at best buy and most computer stores. I would start there and then when it is not thermally shutting down then you can move to software related issues.
Ive heard of folks using a penny (pre 1984 or whenever they changed to copper content) between the GPU and heatsink to fix flakey video issues. But it would be much easier to buy a cheap pcie card to replace the integrated graphics controller.