I have a win7 PC about 12mths old. As long as the PC is doing something eg av scan it is fine. However if the machine idles for around 20mins it freezes, and has to be reset or power cycled. I cant see anything in the event logs as the machine freezes, only the event saying the PC didnt shut down properly. Memtest86+, two passes no errors. Malwarebytes and symantec endpoint find nothing.