Sorry, but I get stuck at another -not too serious- point: In my installation, the menu item "Galerie" shows up double with the Libratus Theme. It does not happen with other themes, thougt.
Any idea or suggestion to get rid of that double entry??

Here's my minimal installation that shows my problem:
http://www.dl9dcn.de/~photo

My guess is that you entered something in
Admin > Options > Gallery > [i]Website url[/i]
You mainly use [i]Website title[/i] and [i]Website url[/i] if Zenphoto is part of another (main)site and you want to be able to link back to that main site.
Otherwise, just leave them empty.

That works perfectly. Thank you so much!