Hi.
My PowerMac G4 with Leopard inside (10.5.7) won't shutdown.
I can logout and switch between users, the G4 awake normally from sleep but when I give the halt command the spinning wheel appear and still spin, even for days!
I pulled the battery, resetted PRAM, NVRAM but the problem is still present.
The only change I noticed is when I booted in single user mode, and, in command line, the system shutdown normally using the HALT command.
But only in single user. If I give the same command using the Terminal into an user or adminnistrator account the system won't shutdown.

Anyone has a suggestion to fix this issue?

Thanks.

Try to fix permission problems on the Disk Utility.

I tried.
First I was logged in as user, then admin and last I booted from install dvd and repaired permission and checked the disk.
Also fsck'd the volume via terminal command at boot in open firmware.
But the problem persist.

I'm starting to consider a re-installing after a format, but this usually happens to a cpu running windows...

Also you can try a "Verbose" boot. Hit Cmd + V after the initial boot sound, and keep them pressed until the system starts. You will see a verbose boot and a verbose shutdown, so you can see wich process is preventing your Mac to shutdown. Try this, and please post the latest messages