I burned Ubuntu Linux onto a CD and restarted my iMac while holding alt to boot into it. The CD didn't show up because I accidentally burned it as a data disc containing the ISO file, but my OS X partition is now for some reason displayed as "EFI Boot." I selected it and it showed the usual startup screen with the Apple logo, then a spinning gear and a loading bar showed up under it. It took 5-10 minutes to get past that screen, then OS X started up like normal. I tried ejecting the CD (which I did absolutely nothing with other than burn and leave in the drive) to see if that was what caused it, but it did the same thing when I restarted and it's still been doing it since. Anybody know what the problem is?