[horde] Login Problems - Horde Groupware Webmail v1.2.3

[Duane Hill]

I just recently installed v1.2.3 on a FreeBSD 6.4 server. I have followed 
the installation instructions with the docs/INSTALL document and have all 
required FreeBSD ports/packages installed. I have seen the test page by 
visiting http://myserver/horde/test.php. There isn't anything on the page 
that indicates errors. I have also performed the tests that are listed 
beside imp, ingo, kronolith and turba. All are clean.

I have edited imp/config/servers.php to reflect using our IMAP server that 
resides at a different location. IMAP connections from the server Horde is 
installed on is able to make successful telnet IMAP connections to the 
other server without error. However, whenever a login attempt is made 
using Internet Explorer 7, the login screen stays up. When I look in the 
logs for Horde, it says the login was successful. When I look in the logs 
on our IMAP server it shows the login was successful and there was an 
immediate logout directly following within the same second of time.

I have searched the web for solutions of which none I could find worked. 
Does anyone have a helpful tip or pointer?