SQL-DATABASE ERROR

Database error in WoltLab Burning Board (): Link-ID == false, connect failed
mysql error: Can't connect to local MySQL server through socket '/tmp/mysqld.sock' (2)
mysql error number: 2002
mysql version: unknown
php version: 5.2.17
Date: 05.02.2012 @ 00:46
Script: /forum/register.php
Referer: