Yesterday I had to boot into Windows XP via Bootcamp to look at something for school. My iMac froze hopelessly, so I restarted. Now, it will not boot up. I can get to the Windows XP logo and then the screen goes black. To make it worse, the keyboard and mouse are completely unresponsive, so I cannot bring up the start up disks to boot into OS X. I have tried using my Apple bluetooth keyboard and mouse as well as a wired USB keyboard and mouse for Windows. I have also tried completely unplugging the computer, to no avail. There is a disk in the drive that I can't get out, as well. Any suggestions? Help? I am about 90 days out of my warranty with Apple.