dovecot - Apr 2006 - unlink a directory

Hi,

Occasionally I get an error message in my dovecot log when, in
evolution, I click on the inbox:

dovecot: Apr 21 00:07:06 Error: imap(admin):
unlink(/home/admin/.maildir/cur/1145393825.P23027Q0M159929.terminator.odyssey.nl:2,ST)
failed: Is a directory

Instead of the message being delivered as a file it appears to be
written as a directory. Deleting those directories solves the error
message from reappearing.

Any ideas?

I use FC5, dovecot-1.0-0.beta2.7, postfix-2.2.8-1.2,
procmail-3.22-16.2.1

Regards,
Alfred