Last week, we saw that Finale 2006 can hose certain files stored in the Application Support folder of your library — that’s not just your Finale preferences, but even things like your Apple Address Book. I’ve just gotten a link to an online updater; run this prior to the Finale 2006 upgrade, and you’re saved. Anyone out there who’s upgraded? (Or did I scare you all off?) In the meantime, I’m waiting for the shipping version of Sibelius 4, which is the program most of my scores are in.
…technically, it doesn't hose one's preferences. It removes contents of the ~/Library/Application Support folder, which can contain contacts for the Address Book, iCal entries, etc. Still, it sucks nonetheless.
Application Support is the folder in question, but many applications include preferences and other vital content there. Anyway, worth running the fix so that you don't find out!
Even better, avoid the original installer DVD and wait for the replacement