From what the MakeMusic folks told me, the registration problems occur in older versions of Finale because in a Mac OS service update, the Apple folks changed something the old Finale registration process relied upon. They had to do a lot of recoding (so they claim) to implement a new registration process, so they wouldn't provide it as an update (bug fix) to older versions; you have to upgrade ($$) to a recent version. They did release a free utility you could run to clear out the registration, allowing you to reregister, but it doesn't work reliably and the new registration won't stick. Because I normally run using a user account separate from my administrator account (registration must be done as an administrator), whenever I'd restart the program as a user, the registration test would fail again.

Since upgrading, I haven't run into a registration problem. I'm still running Leopard (Mac OS 10.5) and only upgraded to PrintMusic 2010--2011 looks like another upgrade that adds nothing of use to me.