When I click on the tab "Edit", in the admin toolbox, I get this errors:

Notice: Use of undefined constant ALBUM_RIGHTS - assumed 'ALBUM_RIGHTS' in /data/vhome/vhost0342/http/zenphoto/zp-core/admin-edit.php on line 16

Warning: Cannot modify header information - headers already sent by (output started at /data/vhome/vhost0342/http/zenphoto/zp-core/admin-edit.php:16) in /data/vhome/vhost0342/http/zenphoto/zp-core/admin-functions.php on line 256

Notice: Use of undefined constant ALBUM_RIGHTS - assumed 'ALBUM_RIGHTS' in /data/vhome/vhost0342/http/zenphoto/zp-core/admin-edit.php on line 1114.

Everything was working fine when I logged in the last time. Any ideas?

I solved the problem. The constant ALBUM_RIGHTS must be EDIT_RIGHTS. Now it works fine.

Well, ALBUM_RIGHTS and EDIT_RIGHTS are two separate things actually. I have not seen that. What zenphoto version was that?

There is no such define as EDIT_RIGHTS any more. Sounds like you have a mixed bag of zenphoto script files. You should be sure you upload the complete set of files. It almost always causes problems to mix files from different releases.