[imp] Problem login from network - local login is ok

[Nextasy_74]

Hallo Friends,

i have installed Horde Webmail Edion 1.0 RC2 on a LAMPP system running 
on debian. Also installed is apache 2.2.3, php version 5.2.0  and all 
necessary modules. The database is mysql version 5.0.27. It all based on 
the XAMPP System published from Apachefriends.de (see 
http://www.apachefriends.org/de/xampp-linux.html). My mailsystem is an 
exim4.5 installation with a dovecot imap server.

i  start the setup script located in scripts/setup.php and everything 
went fine. The database and the tables were created and  i choose an 
admin user. The problem, that i have is, that i cannot login to the 
horde system from a computer in the network. The horde log located in 
/temp says "Login success for user [192.168.1.101] to {localhost:143} 
[on line 152 of "/opt/lampp/htdocs/horde/imp/redirect.php"]" but i 
returned to to login screen. I dont see any menu or something. For 
troubleshooting, i login to the linux system an tried it with a console 
web browser (links2). And what should i say? It works...so, i cannot 
figure out, what the problem is. I tried several browser and computers. 
An another mail system (roundcube) works good, but i will change ist to 
horde/imp

It would be nice, if somebody could help my

Thanks in advance

Nextasy