How about give us a little more information url to board maybe a test login. Also writing the whole request in English or German
Lucky I took 3 years of german
Yes Fotos verarbeiten is Images Processing although you know that better than I since your using the board in german.
Looks to me like your having server issues with connections.
PM me a link and I can try an upload and see if I see anything that can help and send link to phpinfo