Mail.app (v5.0) in Lion doesn't see my IMAP folders

Question

Pulling out my hair on this one. I have a fresh, clean install of Lion running. I setup Mail.app to work with my IMAP server (dovecot-1.0.7-7.el5_7.1 on CentOS release 5.7, using Maildir for all folders, including the 'INBOX').
It connects fine and has full read/write access to my INBOX, and can send via my SMTP server. But my "other" IMAP mailboxes do not show up.
They show up fine in Snow Leopard (v4.5 (1084)), on my iPhone 4S (iOS 5.0.1 (9A405)), on my first-gen iPad (iOS 4.3.3 (8J3)), in Outlook (v14.1.3 (110805)), using SquirrelMail... It's only the new Mail.app that doesn't 'see' the mailboxes.
If I use the Mailbox -> New Mailbox... menu item to try to manually add/create an existing IMAP mailbox, I get a dialog box: "The mailbox "<name of mailbox>" could not be created. The mailbox "<name of mailbox>" already exists."
If I use the same menu command to create a new mailbox, it's created successfully, and shows up under the server's entry in the left-most pane.
So frustrating.
Am I missing something obvious? Or arcane?
Thanks,
Chris

Answer 1

Hey, thanx for your reply.
I have already sent to wd support and the answer which i took back is that:
"Therefore drive itself is fine and issue can be related to your operation system which do not mount the drive properly. If it is possible, please check system updates to be sure that issue is not caused by the OS bug and contact Apple support in this matter to check the problem with them."