Sounds familiar (Score 1)

This sounds like the cheap capacitor problem that was affecting PC motherboards last year. My ABit KT-133 was experiencing the exact same symptoms you describe, it would work fine until I turned it off, and then it was a crap shoot if it would boot up again. Here's the /. article: http://slashdot.org/article.pl?sid=02/11/04/175121 0 I know it's an Apple, but if you can get a look at your capacitors, on the motherboard and in your power supply, see if they have bulging tops or any leakage. Mine were just bulging a bit, but it was enough to be a problem. If it is a capacitor problem I'd be mighty pissed with Apple for buying such crap, especially at the prices they charge.