Was trying to install Windows XP through BootCamp. The installation did not go through, and I quit it. After I tried to restart the computer however, it kept going to a black screen with a blinking _ on top. I restarted, pressing the "option" key and the only partition that shows up there is one for Windows. I can't see one labeled "Mac" or something like it anywhere. I tried using the Repair Disk Utility but it won't actually give me the option to repair ir. Help?!