So I inherited a broken iMac, 17" white. When it turns on, it shows a gray screen with a folder that shows a ? and the Mac happy face. I know it means that it can't find or boot to the operating system, but don't know how to fix this. When I put an OS disc into the iMac, and hold C, nothing happens. I hold option and it boots to a screen that shows two squares, one is refresh, one is an arrow pointing to the right > I click both and nothing happens. I took the harddrive out and re-installed the OS to it, reinstalled it, nothing happens. The harddrive runs perfectly fine so no problems there. What gives?