Solved Unexpected Shutdown & memtest

I built an HTPC & every month or two I get an error message. It usually varies slightly but always seems to come back to an unexpected shutdown per the Events Logs, at least from what I can figure out. But it never says what caused the unexpected shutdown. The last 2 times a recording was interrupted & then restarted. IOW Windows 7 rebooted by itself. But those are the only times I'm have a...