[imp] Can't log in to IMP 4.1 - Unexpected response from server

[Dan Brown]

I just installed Horde 3.1/IMP 4.1 this evening, and I'm having trouble
logging in.  When I try to log in to IMP, it sends me back to the login
screen with this message:

 Unexpected response from server to LOGIN command.

The system log shows slightly more information:

 Unexpected response from server to LOGIN command. [on line 42 of
"/home/e-smith/files/ibays/Primary/html/test/newhorde/imp/login.php"]

I'm running PHP 4.3.10, Apache 1.3.27, and dovecot 0.99.10 as my IMAP
server.  Where should I look to try to track this down?

-- 
Dan Brown, KE6MKS, dan at familybrown.org
"Since all the world is but a story, it were well for thee to buy the
more enduring story rather than the story that is less enduring."
 -- The Judgment of St. Colum Cille