1) I had a second hard drive in that machine, that I was using as a swap disk, so I put Leopard on it. It installed fine. The good thing was that I could see my old disk, and although it was clearly broken by the Leopard installer, I was able to get data off the disk. If you are having this problem, you may be able to load Leopard on to another disk (be it an external firewire or internal disk) and you may be able to salvage you data.

2) I then tried to see if I could repair the disk using Disk Utility. Neither the Tiger or Leopard Disk Utility (from the cd or from the hard drives) would fix the drive in question. I got a yellow or red exclamation point with a message to the effect that the ‘keys were out of order’ when I tried to verify the disk.

3) I downloaded a copy of Gentoo Linux for ppc, burned it to CD using the mac burning program, and booted my mac with that linux disk. I could again see and navigate the disks using the command line. If you are comfortable using the command line, you may be able to get your data off your hard drive that the Leopard installer broke this way.

4) I tried all the tricks I know for repairing the disk while I had it booted up with Gentoo Linux for ppc - like fsck and partitioning tools - but I could never repair the broken disk disk.

5) If you are trying to copy the USERS directory (which is probably what most people want to get off their mac when moving or upgrading a system), you may have to set up a root account if you are booted into OSX. If you try to copy the files and you are logged in with your normal account, you may run into permissions errors when you want to copy other users accounts.

While trying to figure out how to fix this problem, I found several people who suggested using a program called DiskWarrior and who claimed to have success with it. I did not have a copy and I had gotten all my critical data off the disk that Leopard broke, so I did not purchase a copy of Disk Warrior. But, if you really must have that data, it might be worth exploring it.