My 4 year old Windows 7 PC had always been good at going into hybrid sleep at the times that the power settings indicated. However, just a few days ago it stopped doing that altogether. I can still put it to sleep with keyboard shortcut, etc., but it will not go into sleep on its own. I've fiddled with the power settings and it makes no difference. Sometimes I notice that the hard drive light comes on for an instant every few seconds -- an observation more than an explanation. Why has my 4 year old stopped wanting to sleep? What's a mother to do?!