Hello Axel,
the server which is serving "gallery.menalto.com" has no connection, or relation to your server in any way.
If you installed our Software "Gallery" then this software runs fully independent on you server.
An error 500 tough might be a result of some Gallery settings.
But this is a result of your Apache configuration.
You can either adjust these Apache settings,or change/remove the settings in the Gallery .htaccess files.
Greetings,
Jens
--
Last Gallery v1 Developer.
Tryout the TEST-Version of Gallery 1.6