Hmm, IIRC, there is a problem with using German language FS2 and FSOpen. Can you set it to English? Start -> Run, type, regedit, go to HKEY_Local_Machine\Software\Volition\FreeSpace2 , Double - click on "Language", and type:
and then hit enter. EDIT: As is mentioned in this
thread. Then, try it again. Does this work?