Discovered a curious problem with OSX Leopard where I was unable to disable Root from the Directory Application (/Applications / Utilities / Directory Utility ---> Edit / Enable Root User).
What happened was that due to an error I needed to use the OSX 10.5 Leopard DVD to start and change the Root password, which had the effect of enabling Root. I logged in as Root from a normal start, got the problem fixed, and then needed to disabled root.
The Directory Utility never saw that Root was enabled.
The answer was to do it from the command line:
$ dsenableroot -d
this command does quite a bit so you can read about it from the man page:
$ man dsenableroot