My computer crashed today and hasn't been able to boot back up since. It gets to the grey screen with the Apple logo and stops. The fan then ramps itself up to overdrive. I've started it up in target disk mode and repaired it using Diskwarrior on my macbook. It had to repair quite a bit and then it showed up on the desktop of the laptop. I can read, write and pull from it. I then ejected the powermac and started it up again to find the same problem persisting. Any ideas besides the reinstall?