[chrishajer]

To determine if it’s your host configuration, do this. Log in to your forum as keymaster, go to Settings > General, and under “Pretty Permalink Type”, choose the first option None.

http://www.oltrelebarriere.net/forum3/bb-admin/options-general.php

Then try your forum again. I bet it will work which points to a problem with your host and the rewrite rules you’re trying to use in .htaccess.