Clockwork requires OS X 10.4, and you should see a nice warning dialgue when you try to launch it on an earlier version of OS X. Unfortunatly it appears that some versions of OS X 10.3 and 10.4 fail to show this warning and instead fail and print:
RegisterProcess failed (error = -50)
in the Console.app. I don’t have control over this, hopefully it will get fixed by Apple soon.
Make Clockwork work on 10.3
I just learned that Clockwork will run on 10.3 if you modify it’s plist. To do this:
I think some things such as AppleScript won’t work properly, but I’ve been told that in general Clockwork will work. I no longer have 10.3 to test on.