bacteriano, please copy here (between backticks) the settings you have set inside of the plugin, between 'automatic' and 'use_ajax'
I have many, many checks to prevent happening what you seem to have in your database (the storing of wrong info into user meta data) so I don't see how it's happening.
Essentially it must be grabbing $user->bb_reputation from user # 0, which is very wrong.
I have a strong suspicion that you have a typo in your settings.
You can also try 0.0.3 when it updates on bbPress.org - I put in some additional checks to deal with your data corruption to try to fix the values on the fly. Anyone with the strange data in database has lost their points/history however, sorry. If you delete the bad values (the ones with the long string instead of a simple number) it will attempt to re-calculate it.