I had the same problem and indeed it was because that first forum wasn’t created, and indeed because my server runs php4 by default (but I can override to php5 via .htaccess). Of course, I didn’t see this thread until after the fact.
My question: what are the three (or more, or less) files I need to *remove* so I can start the setup over again under php5 and get things working? I assume bb-config.php is among them, but what are the others? What files make bbpress realize it is already installed? Should I just drop everything and start over?
