My hard drive had some hiccups today. It ended up getting to the point where it couldn't boot... just got stuck at the white screen with the gray spinning wheel/gear. I assumed it was a problem with permissions, maybe a small disk error. I popped in a backup boot drive, and ran disk utility... fixed the permission errors, but there were disk errors it couldn't repair. I tried running DiskWarrior, which appeared to remedy the problem: Disk utility no longer reported any errors of any sort. When I attempted to boot from the original drive again, it hung once more on the white screen/gray wheel. To sum up, the drive appears to be in perfect condition. But I still can't boot from it! Any suggestions?