My friend formatted his hard drive, so he could install windows 7 with a clean install. Even before this he could not access bios, but now when he tries to turn on the pc he gets a message "Disconnect Drives Without an Operating System. So he unplugs the HD and turns on the PC with the install disc in after the disc starts to boot he plugs back in the HD and the disc boots up the installation. After that the installation will not pick up the HD it does not show up at all. The PC he owns is a HP all in one it came with windows 7 and he put windows 8 on it didnt like and wanted to go back. Im not stupid with computers but ive tried everything i coould think of and it just doesnt work.