Overheat? The fans revved and suddenly I could use nothing but the cursor. Had to hold down the power switch to kill all and then re-power & startup. I wasn't doing anything unusual, but I had 7 apps open and was amid an auto-backup to TimeMachine. Just a little disillusioned and concerned, wondering if anyone else there has experienced a hard freeze like this. macbook pro 17" 2011 Mac OS X (10.6