doc_bean raises a good point. Sometimes random reboots can indicate the impending failure of a component.
This place http://www.pcpitstop.com/ has a suite of tests and a good afteraction report; I highly recommend it for a quick (no more than 10 minutes) series of tests that will point up potential hardware & software issues. NOTE: it will require you to authorize the download of their ActiveX testing module, to conduct the tests. I promise it's harmless.
Bookmarks