01. Boot from the 'Tiger Install DVD', or another hard disk drive with MacOS X 10.4.x installed.
02. Launch (open, run) 'Disk Utility' and perform a 'Repair Disk' (at least twice), and 'Repair Disk Permissions' (at least twice) on the G4 Powerbook.
03. Reboot to the G4 Powerbook.
Reply with your results.