[horde] Everybody can log in as administrator without password

[horde@a1v.de]

I installed Horde 3.0.5 (and IMP) from the stable releases ftp site.
It works fine, but everybody can log in as administrator without password.
There is a /admin directory although it is no CVS version.

How can i change that?
Thank you

----------------------------------------------------------------
This message was sent using IMP, the Internet Messaging Program.