Mid 2007 IMac Snow Leopard 10.6.8 with the operating system on one partition and files on another. 50 + gigs available on the operating system partition. On boot up I get a blue screen then a grey screen with the flashing question mark. Booting from the Snow leopard install DVD I get to the installation program up to where to install the operating system then the installer cannot seem to find a valid disk to install Leopard on. The screen remains blank, and cannot continue. Is this a sign of a dead hard drive? there are no grinding sounds and an hour before I was watching Two and A half Men which I I had recorded with Elgato EyeTV Hybrid. After that I had the spinning beach ball, did a hard boot and after that, the blinking question mark. Any thoughts?