Take it to the Genius Bar. You might have an issue with you SIM. The SIM is what manages power in the unit and will get confused on how much power to send to certain parts. It should take about 10 minutes for them to re-program the part by plugging in a special cable and restarting the Mac. What model do you have? Cuz from what I have noticed, issue with the SIM has occured in the Macbook models.