One of the issues looks like a www/non-www issue. When you go to the link provided it eventually redirects you to http://nettomo.de/ubbt/ubbthreads.php

That's the typical cookie issue with the www/non-www urls. It looks like the forum was setup just as http://nettomo.de


The file/picture issue, I might need to get admin access and ftp access so I can take a closer look.