Hello, Having Hard Drive issues with iMac. With the original hard drive in the machine it starts up to the white screen with spinning circle thing and then completely powers off. If I hold down option I can go to the diagnostic partition and it doesn't shut down. If I try to verify or repair the drive it fails. Therefore I am assuming it is a bad hard drive. So after disassembling the unit, thanks to help from the toilet plunger to remove screen cover, I replaced the hard drive which was a Western Digital with a Seagate Hard Drive claiming it is compatible with Mac OS X.5 or higher, I boot up with a Snow Leopard disk, start the install process and it doesn't see the hard drive. I tried several old hard drives I have laying around and they also aren't detected, however the original one is so I am not believing it is a cable issue. Now what I am wondering is this...Do I need to prep the drive somehow or format it? I tried it as is out of the box and no luck. I do not have access to another Mac but have several Windows PCs that I can use. I tried formatting the drive FAT on a Windows 7 PC and still no luck. The other problem is this. My friend does not have a OS X install disk that came with the unit. I do however have a OS X Snow Leopard install DVD from a different mac. Do I perhaps need the original OS X version install disk that came with the unit. My friend had the old hard drive running with a copy os Lion that she paid for. I have tried combing thru Google and websites trying to find these answers but haven't gotten anywhere so my hope is somebody here will be so kind as to provide the missing piece of the puzzle that I am over looking. Thanks in advance!