Although, the reports never give a clear answer, only clues. I would lean toward hardware. I base my answer on the following. One of the reports clearly indicated that it was hardware and you have reinstalled your OS and the problem still occurs. One usual cause of hardware problems is memory, lets give that a test, its easy. Then we can move on. http://www.geekstogo.com/forum/topic...ing-memtest86/
If it is not hardware, I would certainly think its a driver.
Regardless of the cause, Lottie is correct, you should always be up to date with the SPs