I just bought two alu 20" iMacs to give as Christmas gifts, and they each came with a Leopard drop in disk. When Leopard is nearly finished installing, the iMacs shut off. When I restart them they start the install process over again. There are no error messages. The machines just power off and do not restart by themselves. This is happening on both of them! I didn't skip the DVD check at the start of the install, and there were no errors. I have not installed any software or peripherals. I did do software update before starting the upgrade. Does anyone know what is happening or how I can fix this? Please help! Thanks!