I had this too. It was driving me nuts. My problem ended up being with another plugin called Forum Restrict. If you have that plugin installed, then it’s probably the same for you. If not, you should try disabling all your plugins except for bbPress and see if it goes away. I don’t think bbPress itself is the problem.
If you do have Forum Restrict, the problem is with the forum_title() and topic_title() functions in index.php. The fucntions echo a variable called $ttitle which is where the black text above the header comes from. It looks like the text was meant to be inserted somewhere else, but it’s not working properly.
