[chrishajer]

Are you using any plugins? If so, disable them.

Are you using a different language file? I see the .no in your domain name.

Also, do you integrate with WordPress, and if so, what version. And what version of bbPress too.

The only other error I found close to this is here:

http://support.bbpress.de/topic/anmeldung-nicht-moglich-bitte-hilfe

That’s in German, which made me think of the language file. The complaint there seems to have something to do with a XAMPP installation. What server are you running on?