You're the 2nd person to say their IBook G4 won't do a safe boot. Perhaps they're not designed to. Oh well. Try repairing permissions anyway whilst it's started up normally.

What you can do is start up with the startup disk, repair disk. (But don't repair permissions from start up disk!!!)

Are you able to mount the dmg file?

Do you have stuffit expander on your system? Some people have problems with stuffit interfering by trying to mount the dmg file. Whilst it can, on some people's systems it doesn't work correctly.

BTW someone also was having similar problems: Limewire won't install