Your Portal Version: 1.0.6
Your phpBB Type: Standard phpBB3
MODs installed: No
Your knowledge: Beginner
Boardlink: http://www.ford-taunus.net/portal.php

PHP Version: 3.0.7-PL1
MySQL Version: MySQL 5.0.91-log

What have you done before the problem was there?
update 1.0.2 to 1.0.3 and 1.0 ...