I am having some behavior issues with my powermac. In system preferences, I told my computer to go to sleep after 3 minutes (for testing) I also told the display to go to sleep after 3 minutes. After three minutes, the display sleeps, but the powermac keeps on chugging. After 15 minutes, it is still awake...what is causing this to happen When I push the power btton, it falls asleep instantly..??? Should I contact apple support?