[imp] login not working

[Keith H.]

Greetings,

I'll start by saying that I've read through the archives at google and 
still can't seem to solve the problem. I have fixed other issues thanks 
to the archives though. But this one last issue just won't die.

Here's what my setup is like:
RedHat 8
PHP 4.2.2
courier-IMAP 2.0.0
Horde 2.2
IMP 3.2
I have updated the PEAR installation to meet horde's requirements
I have configured the registry to use IMP to login
Here's the configuration for IMAP in:

/horde/config/horde.php
    $conf['auth']['driver'] = 'imap';
    //tried with and without /notls
    $conf['auth']['params']['dsn'] = '{localhost:143/imap/notls}INBOX';

/imp.config/servers.php

    $servers['imap'] = array(
        'name' => 'IMAP Server',
        'server' => 'localhost',
        'protocol' => 'imap/notls',
        'port' => 143,
        'folders' => 'Maildir/',
        'namespace' => '',
        'maildomain' => 'mail.MYDOMAIN.net',
        'smtphost' => 'mail.MYDOMAIN.net',
        'realm' => 'MYDOMAIN.net',
        'preferred' => ''
    );

and in PHP.ini:
extension=imap.so

phpinfo shows the following info for imap
IMAP c-Client Version    2001
SSL Support    enabled
Kerberos Support    enabled
'--with-imap=shared' '--with-imap-ssl'

here's the error in horde.log
Jul 26 22:01:00 HORDE [error] [imp] FAILED LOGIN 11.22.333.444 to 
localhost:143[imap/notls] as USERNAME [on line 282 of "/var
/www/horde-2.2/imp-3.2/lib/IMP.php"]

courier is running

this is the result from the IMAP test in test.php
server="localhost" user="USERNAME" mailbox="{localhost:143/imap/notls}INBOX"

bool(false)

So, I've hit a brick wall. Can anyone offer any insights as to what I 
may be missing or need to re-configure.
If I've left out some information that you need to know to answer me, 
please tell me what more you need to know.

thank you,
 - keith