I have a G4 Mirrored, Dual 1.42, w 2gb ram
When Upgraded to tiger (any mini version) I'm not able to finish a shutdown or restart. I've installed clean, and over my 10.3.9 with the same results. I have removed my third party hardware (USB 2 card and extra firewire card), I have run OnyX, TechToolPro, Disk Util, Apple hardware test (although not the repeated extended version) and nothing has made a dent in it. I've reset things through open firmware. So in my mind it looks as though its left with something from OS problem.
Is there a particular log file I can look into, or cache or preference I can delete? Other than this the system is stable and fine, just can't get it to finish a shutdown routine.