[Dovecot] Folder Management Dovecot >1.2

[Carlos Candeias]

Regardless of the mail client no user can modify, move, delete or
subscribe an imap folder with Dovecot >1.2.1 (meanwhile 1.2.5). Dovecot
apparently have some dotlock problems:
(From dovecot.log)
Oct 02 14:58:19 IMAP(jcci): Error:
fchown(/candeias/home/jcci/.mail/Maildir/subscriptions.lock, -1,
0(root)) failed: Operation not permitted (egid=1003(management), group
based on /candeias/home/jcci/.mail/Maildir)
Oct 02 14:58:19 IMAP(jcci): Error: file_dotlock_open() failed with
subscription file /candeias/home/jcci/.mail/Maildir/subscriptions:
Operation not permitted
Oct 02 14:58:20 IMAP(jcci): Error:
fchown(/candeias/home/jcci/.mail/Maildir/subscriptions.lock, -1,
0(root)) failed: Operation not permitted (egid=1003(management), group
based on /candeias/home/jcci/.mail/Maildir)
Oct 02 14:58:20 IMAP(jcci): Error: file_dotlock_open() failed with
subscription file /candeias/home/jcci/.mail/Maildir/subscriptions:
Operation not permitted
Oct 02 14:58:20 IMAP(jcci): Error:
fchown(/candeias/home/jcci/.mail/Maildir/subscriptions.lock, -1,
0(root)) failed: Operation not permitted (egid=1003(management), group
based on /candeias/home/jcci/.mail/Maildir)
Oct 02 14:58:20 IMAP(jcci): Error: file_dotlock_open() failed with
subscription file /candeias/home/jcci/.mail/Maildir/subscriptions:
Operation not permitted
Oct 02 14:58:21 IMAP(jcci): Error:
fchown(/candeias/home/jcci/.mail/Maildir/subscriptions.lock, -1,
0(root)) failed: Operation not permitted (egid=1003(management), group
based on /candeias/home/jcci/.mail/Maildir)
Oct 02 14:58:21 IMAP(jcci): Error: file_dotlock_open() failed with
subscription file /candeias/home/jcci/.mail/Maildir/subscriptions:
Operation not permitted
Oct 02 14:58:21 IMAP(jcci): Error:
fchown(/candeias/home/jcci/.mail/Maildir/subscriptions.lock, -1,
0(root)) failed: Operation not permitted (egid=1003(management), group
based on /candeias/home/jcci/.mail/Maildir)
Oct 02 14:58:21 IMAP(jcci): Error: file_dotlock_open() failed with
subscription file /candeias/home/jcci/.mail/Maildir/subscriptions:
Operation not permitted

This was an attemt of changing a subscription.
Another weird point: I can create an IMAP folder although it does not
show up in the folder list. But the new folder is in the subscription
list, just marked as unsubscribed and there is no way to change that.
This problem is safely reproducible and I wonder whether I should be
really the only person having this trouble.
I'm using MAILDIR and simple plain test authentification (internal mail
server).
The location is mail_location: maildir:~/.mail/Maildir which means a
subfolder in each user's home directory.
All homes are exported to NFS, but the Dovecot is just on the same
server and thus accesses locally.
Downgrade to version 1.1.17 solves all problems.
Archlinux x86_64, Linux 2.6.30
It would be really great if somebody could understand the cause and
suggest a solution!