I've never run across this problem before and cant find anything on it, so I will make an educated guess.
You may want to check your Ram to make sure its not on its way out. You can run a test on it, try Sandra located here: http://www.sisoftware.co.uk/sandra
Run some in-depth systems tests with that program and see if you get any errors.
Run some in-depth systems tests with that program and see if you get any errors.