[Dovecot] Dovecot tries to create bogus files in /var/mail

After upgrading from 0.99.2 to 1.0rc14, I started seeing log-entries like:

Nov 16 12:56:22 corbulon dovecot: IMAP(mksarch): mkdir_parents(/var/mail/mksarch/.imap/INBOX) failed: Not a directory Nov 16 12:56:51 corbulon dovecot: IMAP(anat): open(/var/mail/anat/inbox, O_CREAT) failed: Not a directory Nov 16 12:56:51 corbulon dovecot: IMAP(anat): mkdir_parents(/var/mail/anat/.imap/INBOX) failed: Not a directory

And my IMAP client (KMail) shows up error message with "Internal server error". The files in /var/mail/ are just that -- files (in the bad old Unix mbox format), and not directories, why is dovecot treating them as directories?

Please advise... Thanks!

-mi