Squirrelmail 1.4.2 integration problem w/ dbmail-imapd 1.2.2

I have posted this problem to the SquirrelMail list already, but I am 
starting to question my initial assumption that it is a SM configuration 
problem.  I am starting to wonder whether I am doing something wrong on 
the DBMail side.  I could not find anything like this in the archives.  
We are preparing to deploy SM for our customers and I've got an install 
on our test box.  All services are running on the same box (MySQL, 
Apache, Postfix/DBMail, etc.), and the browser is on the same box as well.

The basic problem is that when I correctly login to Squirrelmail I get 
an error message: "You must be logged in to access this page."  This is 
not an HTTP authentication window; this is the resultant PHP document 
from logging in.  (When I login incorrectly, I get the expected "bad 
password" massage instead.)

I have turned the trace level up to 5 on the dbmail-imapd server.  
Unfortunately, it does not log the responses to client commands, only 
the commands themselves.  (Feature request?)  But here are the four 
commands I see from the client.  Does this look strange to anyone?

A001 LOGIN "tld_domain__user" "password"
A002 CAPABILITY
. LIST "INBOX" ""
A003 LOGOUT

The IMAP server logs do not show any errors.  It can talk to MySQL just 
fine, etc.  (The POP3 daemon works fine, and I can use this mailbox via 
IMAP in Mozilla 1.6 without problems.)  I created the account with this 
command line:

$ dbmail-adduser a tld_domain__user {crypt:}password 0 0 user@xxxxxxxxxx

I have made no changes to the "user", "mailboxes", or any other tables 
by hand.  All flags in the INBOX row for this account are set to 0 (the 
default for all), and 'permission' is 2 (the default).

Does anybody see any configuration error on my part with DBMail?  Has 
anyone seen this exact problem before?  Thanks for your attention; I 
promise to post the resolution when I reach it.

--
Will Berry
Co-founder, Second Brain website hosting
http://www.secondbrainhosting.com/