thanks mark, and thanks mike.. i was finally able to pinpoint the problem - anyone who had \'Forum Default\' set in the UserCP would be having this problem. this is due to a style conflict i had between vBulletin and vBPortal. i\'ve fixed it, and all modules should work fine for everyone now.
i\'m just surprised no one mentioned anything sooner... though now that i think of it, someone mentioned getting a blank page for Chat a while back, and this would be the same problem...