Try a Return to Factory Settings under the Opts menu, it may be that something in one of BB's volatile files has become courrupted. That's always a good thing to try when BB doesn't do something it is supposed to do.

You may also have to hit New and start the songfile over from scratch, too, after the Return to Factory, -- if the songfile became corrupted.

I don't think this is a program bug or we surely would have found it or heard about it by now.

--Mac