[fel64]

Is there a problem with your wordpress install too?

To fix bbpress, you need phpmyadmin or a similar tool. Login, go to your bbpress database. Not certain what it’s like on 0.9, but you probably need to go to the bb_topicmeta table and perform a search (or browse through) to find a record where the meta_key is wp_table_prefix. Try deleting that record. Without that setting I think bb would look for its own users again.