[horde] Help needed - install problem with blank login page

[Martin Schneider]

After installing the "Horde Groupware Webmail Edition 1.2.4" I receive a 
blank page
when calling "http://<server>/horde/imp/login.php".
Therefore I cannot proceed configuration inside the application.

At /tmp/horde.log following entry is written:
Oct 07 16:54:24 HORDE [error] [] Guest user is not authorised for 
Address Book. [pid 4950 on line 1706 of 
"/opt/lampp/htdocs/horde/lib/Horde.php"]
Oct 07 16:54:24 HORDE [error] [] Guest user is not authorised for 
Address Book. [pid 4950 on line 791 of 
"/opt/lampp/htdocs/horde/lib/Horde/Prefs.php"]

Steps I have already done:
1. Prepare system and unpacking horde
2. Run scripts/setup.php (Configure database setting, Create database or 
tables)
Mysql DB creation and runtime access to DB looks OK.
3. Added IMAP infos to imp/config/server.php file
4. Output of http://<server>/horde/test.php also looks completely OK
 
I've already searched in mailing archive, wiki and google but does not 
found a solution.

Thanks for any hints
Martin