What Shadow listed won't fix the reboots, but it *will* give an error message, so you can track down what is going on. I was having the same problems, turned off the "automatic reboot", and it gave me a big blue screen that I could read before I manually rebooted with information so I could track down the problem. I think the one I had before was like IRQL_NOT_LESS_OR_EQUAL, and listed nv4...somethingsomething.dll. I did a search on google, and found it was my network card, which I then replaced.
If you can't find anything on Google with the message, feel free to post here or email me, and I'll track it down. I'm good at finding error messages.
