[Dovecot] Timeout while waiting for shared lock for index file /var/mail/XXX/Maildir/dovecot.index

[Giannis Zachariadis]

Hello,

I'm using dovecot v1.0rc23 for about 500 users since february with no 
particular problems. I'm using Maildir format and ldap authentication.
A recently added user can't check his mails any more. In the logs I get

May 23 14:35:58 mailsrv deliver(XXXX): [ID 702911 mail.error] Timeout 
while waiting for shared lock for index file 
/var/mail/XXXX/Maildir/dovecot.index

The user connects with IMAP to retreive his mails. Currently I can login 
to his account with pop3 and retreive the mails, but when it comes to 
IMAP I get this error and no mail at all.

thanks in advance,
-- 
giannis.