I'm suffering with a similar problem.
Seagate 1TB Slim Drive--orig PC format, now Mac.
It works fine on an old G4 Mini, but freezes my GA-Z77X-UD5H / i5 3570K running 10.8.4.
Updated USB 3.0 universal drivers.
Maybe a BIOS setting I'm missing?
I'd hack the models that can't run Leopard (<867 Mhz G4). If they can run Leopard they can live out their final years running the current version of iTunes as a server.
Well it was true when I wrote it... but as of Sept. 12, 2012 the latest version DOESN'T run on PowerPC anymore...
Well reading comprehension was never one of my talents but did you say where you got the kit for the back panel?
Quote: "Next I used a Kit I purchased with a Laser cut Persplex I/O backplate.."
I've got an old Blue and White G3 that I'd love to revive in all it slightly tacky glory. (I don't have the then matching CRT monitor unfortunately)
I'm following this thread, wishing you success. Keep us informed of your progress.
Worked for me. I first deleted "Ethernet" from Network in System Preferences.
Created new Ethernet entry in Network in System Preferences.
When I signed in the App Store quick unexpectantly but when clicked it again it started up fine and already...