Here is my problem. I attempted to install Ubuntu along side OS X (which I have done before successfully, but I had a failed Ubuntu Studio install first this time around) and now my iMac won't boot up from the install disk. I have tried resetting pram and installing refit to select the DVD, but every time, no matter what, it gets stuck on the white screen with the apple logo. The DVD spins for a bit then stops and it just sits there, mocking me. Any help would be appreciated.