I have my iMac scheduled to shut down everyday at 12:30 am. Sometimes it will shut down and sometimes it won't. I've only had my iMac for about a month, but am I missing something here? Why won't it shut down automatically. I had it scheduled to shut down at 12:30am, and I was already asleep. I woke up about 3am to get a glass of water and I checked my iMac and I was able to wake it up. What am I doing wrong, why won't it auto shut down?