When I did a fresh install of Panther about 2 weeks ago, it would start up so slowly. I could start Safari, iChat, any other app and Finder wouldn't have even started up. Finally what I did was used Root to create another account and deleted the account that I made. From that, Finder starts up normally. What I'd do, is create a new User, log in as that user, open the app, log out, login as you and open the app. See if that works.
EDIT: NOTE: If you do delete that user, to get him back as an administrator, open NetInfo Manager go to /groups/admin authenticate using the lock button down in the bottom left, then click down the users and click users then click Directory->New Value type in the name of the user, hit ok, update the copy, log out, log in, and there you go.