I am running Win7 on a frankenstein computer, built of brand new parts. Occasionally, it powers down by itself, but only while idle and I haven't used it. Pressing the power button will not turn it back on, but unplugging it, then toggling the power switch off and back on, then plugging the power cord back in will allow it to start. When it starts back up, the desktop is exactly the same as I left it, but everything is not responding and I need to manually reboot. Any knowledge of what might be causing this?