Currently Being ModeratedDec 13, 2013 2:46 PM (in response to srobs)
Are you possibly using Disk Utility installed on the internal hard disk? If you wish to completely erase a startup disk, you would have to start the computer from another disc/disk. See, for example, the link below:
If you do not have access to a suitable system disc, you may want to try an Internet search for an old PowerPC version (dban-2.0.0_powerpc.iso) of a data erasure utility called DBAN instead. Once a bootable CD-R has been created from a downloaded iso file, you could test whether that disc would let you boot the PowerBook G4 (while holding down the C key). Then follow instructions on screen.
Currently Being ModeratedDec 17, 2013 9:08 AM (in response to Jan Hedlund)
Thanks Jan. That solved the initial question, but now I am getting another error. I located my system discs and am using that utility. I select the disc and hit erase. I am now getting an error "Disc erase failed. Cannot unmount disc." Any further suggestions before I go the DBAN route?