I've got a really strange one here; a friend dropped off his G4 450DP yesterday because he couldn't get it to boot up. If you try to boot it into OS X (from the 10.3.9 folume on the hard drive or an OS X utility disk) you get the apple icon with the spinning doodad below right away, but then the apple changes to a different icon altogether; a circle with a slash through the middle, like the red circle/slash from the Ghostbusters logo. Once it gets to that point it sits and sits and sits... the spinning doodad below keeps spinning, but nothing else has happened.
One other thing I tried was target disk mode on my laptop, which worked to a degree; the three volumes on his drive showed up in the finder, but if I clicked on any of them trying to see what was in them or tried to run Disk Utility or DiskWarrior on it, it would take forever to do anything. I started up DiskWarrior on it before going to bed (at 11pm) and when I got up this morning (6am) it had gotten as far as displaying the list of disks, but had the spinning rainbow disk.
The owner of the machine was trying to add a second drive to it when things went south. I'm afraid he might have hose this drive but good.
Anybody ever seen the circle/slash on boot before? Any quick & easy solutions?