[Dovecot] sending of password did not succeed

Hi

Today I have upgraded my Debian server from lenny to squeeze and my email stopped working.

I am using Dovecot 1.2.15 with exim4.

Exim4 is working and mail is being delivered to the mailboxes - /home/ didm.co.uk/peter/Maildir/new etc

When I try to download emails to my I get

"sending of password did not succeed, Mail server mail.didm.co.ukresponded:Authentication failed"

and the server Dovecot error log "utime(/home/didm.co.uk/peter/Maildir/tmp) failed: Permission denied" etc

Help please

Peter