Help! My brand new intel iMac is turning off all by itself. Brought it to the apple store and they gave me a new one, plus a free ext. hard drive, but same problem with new one. Tried disconnecting all peripherals with no improvement. Happens at randoms time while using various programs. Computer completely shuts off... have to wait a minute or two before I can turn the computer back on. Tried resetting the power management settings, no help. The computer isnt going to sleep, its completely turning off. I love my imac, but this problem is driving me crazy.