Re: php warning causing error in bbpress profile.php
You haven’t given us much to go on. You have mu trunk, bp trunk and what version of bbpress? Gotta run 1 alpha 4.
When you try to edit a user profile from bbpress dashboard > users you get the above error? I had problems with bbpress throwing 404s because I hadn’t seen the little link to the needed .htaccess file for bbpress. In case you missed that one its in settings > general > permalinks.
This doesn’t sound like that problem though.
Looks like bbpress is not happy with the info it’s getting about your users. Does mu and bbpress share the same database? If not then you have to point it in the right direction under settings > wordpress integration > show advanced db settings > all that stuff in there.