Guys, my mac keeps on having this problem but sometimes spontaneously resolves itself. I keep running repair on disk utility and it always finds problems... (Happened before already). My sounds suddenly stop working. I've tried resetting PRAM already. I can't leave it in for repair (I bought apple care for this -- MBP 13" base 2011 so it's still under Apple care). Can't leave it with an Auth Apple Service center cause I have classes and I need this... Any advice on how to fix this? I've already tried the headphone/earphone 'trick.' No luck. I don't know how it gets fixed spontaneously before... it sucks cause I really need this now to edit a video. Thanks in advance!