Sorry for the newbie question (I have only had a 15" MBP for two weeks - and have loved every minute!), but does anyone have any idea why my MBP sometimes forces a restart after I reopen the lid? I had it plugged in and sleeping, and then when I opened it up a big power symbol appeared in the middle ot the screen and I was asked to confirm a restart. Have searched the forums to see if anyone else has asked about this, but no luck. Any help?