My new iMac 24-inch, 2.66 GHz, is dead on delivery. Boots to blue screen if non-native peripherals attached (mouse, printer etc.) and it won't mount external drives properly. Got pushed up from tech support to a product specialist who immediately said it was dead on delivery, swap it. Sounds like a logic board issue. Waiting for the next shipment at the Apple store to swap. They were good about it. Everything was documented on the service number file. Hoping for better luck with the next one.