dovecot settings problem (mkdir(/var/lib/dovecot/index/user@domain.tld/.INBOX) failed: Perm Denied)

Hi Jamie,
we started having problems with recent default installs of virtualmin GPL, with the dovecot settings. We found out that users couldnt acces their pop3 account because:

Oct 17 14:36:22 dedicatedbox dovecot: POP3(user@domain.tld): mkdir(/var/lib/dovecot/index/user@domain.tld/.INBOX) failed: Permission denied
Oct 17 14:36:22 dedicatedbox dovecot: POP3(user@domain.tld): mkdir(/var/lib/dovecot/control/user@domain.tld/.INBOX) failed: Permission denied
Oct 17 14:36:22 dedicatedbox dovecot: POP3(user@domain.tld): mkdir(/var/lib/dovecot/index/user@domain.tld/.INBOX) failed: Permission denied
Oct 17 14:36:22 dedicatedbox dovecot: POP3(user@domain.tld): mkdir(/var/lib/dovecot/control/user@domain.tld/.INBOX) failed: Permission denied
Oct 17 14:36:22 dedicatedbox dovecot: POP3(user@domain.tld): Couldn't open INBOX: Internal error occurred. Refer to server log for more information. [2008-10-17 14:36:22]
Oct 17 14:36:22 dedicatedbox dovecot: POP3(user@domain.tld): Couldn't open INBOX top=0/0, retr=0/0, del=0/0, size=0

editing /etc/dovecot.conf and replacing

mail_location = maildir:~/Maildir:INDEX=/var/lib/dovecot/index/%u:CONTROL=/var/lib/dovecot/control/%u

with

mail_location = maildir:~/Maildir

fixed the problem.

Any suggestions?

Thanks!