Marking as resolved due to the addition of the new IMAP_Tree library 
(Ticket #6972).  If this is still an issue, a new ticket should be 
opened.

I use courier-imap as the IMAP server.
I have a folder called ".INBOX.Sent" (probably created by Outlook or 
thunderbird) in /home/rsalmon/Maildir. It appears like this in IMP :
- INBOX
+-- INBOX
      +-- Sent

Removing this folder solve the first issue (not beeing able to see INBOX)

cvs update -Pd -D 06/16/2008 : everything works fine.
cvs update -Pd -D 06/17/2008 :
- I can't see/access INBOX folder with the following 
imp/config/server.php file
$servers['imap'] = array(
     'name' => 'IMAP Server',
     'server' => '127.0.0.1',
     'hordeauth' => true,
     'protocol' => 'imap/notls',
     'port' => 143,
     'maildomain' => 'mbpgroup.com',
     'smtphost' => ''127.0.0.1',
     'smtpport' => 25,
     'realm' => '',
     'preferred' => '',
     'quota' => array(
         'driver' => 'imap',
         'params' => array(),
     ),
     'acl' => array(
         'driver' => 'rfc2086',
    )
);

- I can see/access INBOX folder with the following 
imp/config/server.php file but when expanding the folder tree, a 
vertical scoll bar appears on the main window and not the sidebar like 
it use to be.

/* Example configurations: */
$servers['imap'] = array(
     'name' => 'Courier IMAP Server',
     'server' => '127.0.0.1',
     'hordeauth' => true,
     'protocol' => 'imap/notls',
     'port' => 143,
     'maildomain' => 'mbpgroup.com',
     'smtphost' => '127.0.0.1',
     'smtpport' => 25,
     'realm' => '',
     'preferred' => '',
     'quota' => array(
         'driver' => 'imap',
         'params' => array(),
     ),
     'acl' => array(
         'driver' => 'rfc2086',
     ),
    'imap_config' => array(
         'children' => true,
         'namespace' => array(
             '' => array(
                 'name' => '',
                 'delimiter' => '.',
                 'type' => 'personal',
                 'hidden' => false
             ),
             '#shared.' => array(
                 'name' => '#shared.',
                 'delimiter' => '.',
                 'type' => 'personal',
                 'hidden' => false
             ),
       ),
         'search_charset' => array(
             'UTF-8' => true
         )
     )
);