For the past 6 months or so I've was having problems getting my Macbook to wake from sleep mode. All I got was the black screen. I had to push the on button several times before my Macbook would launch. I took my computer to the Genius Bar on Monday 1/13 and got it back today 1/16. Problem: Logic board, a $312 repair, needed replacing. I am lucky in that I purchased Apple Care which negated me paying anything. Any of you having this problem might want to have your computer checked before the warranty expires.