A new default, Suggest Subject Terms, seems to have appeared directly above the (advanced) search interface box. After entering terms in the search box, BSP now goes directly into the Subject/thesarus screen and prevents any modification to the search. I emailed Doug several days ago since he has the administrative rights to the database and probably can change this but he is not here. Mike is investigating to see if he can do something.
To do a search "the old way" simply remove the check from the Suggest Subject Terms box.