Eternal Beachball of Death

Question

I've spent most of the night and morning attempting to install Leopard on 867 Mhz G4. Plenty of disk space.
After 3 installations - including the most recent Archive and Install - I get only this (same after each installation): When the machine reboots, it almost makes it to the finder. I get the dock and menu bar (though latter isn't completely populated), desktop picture - and an eternal beachball of death.
What do I do now?

Answer 1

You can do a backup of user files either with a File Restore with Subrosasoft Filesalvage, or Prosoft Data Rescue and an external Firewire hard drive, verify the contents of that drive contain all your important data, and move that to another Mac. Or you can put your Mac into Target Disk Mode and see if another Mac can see its data, and backup your important user files that way. Once you know you have all your important user files backed up and they have good content, then you can attempt to repair the non-functioning OS.
Just reinstalling Tiger on it, is not an option, unless you are happily backed up, because just reinstalling Tiger will either wipe your drive and install Tiger, or install a partial Tiger/Leopard system where none of the components work well together assuming there is nothing else wrong with your system. So getting your data safely off your drive first is the priority. You have no idea what is causing the beachball and the malfunctioning OS, it can be simply data corruption, an incompatible drive, an incomplete install, or a drive directory or permissions that have gone askew, or worse a dying drive or hardware failing. Since it can be any of the above, it is vital you get your information off first.