You saying that when you press the power button to intially turn on the Macbook it starts up and is automatically sleeping? Then you have to press power again to wake it? I'm just trying to understand. I know when it sits for a while and goes to sleep eventually you have to press power to wake it but it shouldnt start up sleeping. If it is doing that I would check your EFI firmware version, AKA boot rom. See if it needs any update. Usually you can update it through the normal software update module. If still not luck, sounds like its time to take a trip to the Apple store.