Well.... if you were to call into Apple they would say.
Other than the power, unplug everything else you have hooked to it.
Boot Into Safe Mode
Reset SMC
Reset NVRAM
Go into recovery and run disc repair
Reinstall OS
Call Apple to discuss Hardware service Options...
Do those in order.
To boot into safe mode you do a restart and then hold down shift while its booting up. (If it freaks out and starts flashing and showing crazy lines, don't worry that happens)
Reset SMC by disconnecting the laptop from power, holding down Shift Option Control and the Power Button for 10 seconds (you wont see anything happen), plug it back in and reboot
Resent the NVRAM. When it turns on and you hear the Chime, press and hold Command Option P & R until you hear the Chime 2 more times and then let go and reboot.
Disk repair... While the computer is start hold down Command R. When you get to the OSX Recovery screen click on the Disk Utility and verify the disk and repair if it needs it
Reinstall OS is another option in the Recovery area. It will reinstall the OS but it does not erase your data so its safe.
All else fails...1-800-692-7753...
