[Dovecot] Can't rename mailboxes, any ideas on how to fix?

I am running Dovecot 2.1.12 under FreeBSD, and I use Outlook 2010 with imap to connect to my server. I know I used to be able to rename mailboxes, as I do this every year at year end, but when I went to rename some mailboxes the start of this year, blamo up popped the message "CANNOT Renaming not supported across conflicting directory permissions".

Then only thing that has really been updated here, is Dovecot itself, as I know the FBSD port updates when new versions are released. Any clues on what may have caused this, or how to best correct it?

Howard Leadmon