If I go directly to the PHP file which generates your gallery's XML data, an error 404 (file not found) is displayed.
http://www.foto.pelles.ch/wp-content/pl … llery_id=7
This suggests that either the file does not exist on your web server, or that access to the file is being blocked.
This is the reason why both your gallery settings pop-up window (in the backend) and the gallery (in the frontend) do not display. They require direct access to the 'jb-config.php' and 'config.php' files respectively.
(This has not changed between v1.4.0.1 and v1.4.2.0.)
Please check the following:
(1) Check that all the WP-Juicebox files (including 'config.php' and 'jb-config.php') are present on your web server.
(2) Check that the permissions on these files are not too restrictive. (Permissions of 644 should be fine.)
Also, you could try checking with your web host to see if they have made any changes recently which would be affecting things this way.