If you have enough free space, perform an archive and install. Sometimes, reinstalling the combo update (such as the 10.4.11 combo update) fixes issues like that as well. If you have external media or access to a disk burner, copy the 10.4.11 combo update (for PPC) to it and try running it and rebooting. It really depends on the issue going on to see which is going to be the fastest and easiest way.