My macbook pro keeps getting stuck at the startup screen with the spinning wheel. I have tried booting in safe mode but nothing different happens. I tried booting from the install disc but it keeps ejecting the disc before getting stuck at the startup screen again. Sometimes a folder flashes with a '?' on it a few times before going to the the apple logo with the spinning wheel when trying to boot from the disc. I have tried resetting the PRAM but that didnt work ether. anything else I can do?