Login Failed since Courier to Dovecot Migration

[Aodhan]

Hi,

I migrated from courier to dovecot imap yesterday and ever since my roundcube reports login failed.

error log :
[07-Jun-2013 12:30:01 +0100]: IMAP Error: Login failed for [email protected] from xxx.xxx.xxx.xxx. AUTHENTICATE PLAIN: Authentication failed. in /home/xxx/email/program/include/rcube_imap.php on line 191 (POST /email/?_task=login&_action=login)

imap log:
[07-Jun-2013 12:29:54 +0100]: [912C] S: * OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE STARTTLS AUTH=PLAIN AUTH=LOGIN] Dovecot ready.
[07-Jun-2013 12:29:54 +0100]: [912C] C: A0001 ID ("name" "Roundcube Webmail" "version" "0.8.4" "php" "5.2.9" "os" "Linux" "command" "/email/")
[07-Jun-2013 12:29:54 +0100]: [912C] S: * ID NIL
[07-Jun-2013 12:29:54 +0100]: [912C] S: A0001 OK ID completed.
[07-Jun-2013 12:29:54 +0100]: [912C] C: A0002 AUTHENTICATE PLAIN AGFhQHRoZXBob25lc3RvcmVzLmllAGFvZGhhbg==
[07-Jun-2013 12:29:56 +0100]: [912C] S: A0002 NO [AUTHENTICATIONFAILED] Authentication failed.
[07-Jun-2013 12:29:56 +0100]: [912C] C: A0003 LOGOUT
[07-Jun-2013 12:30:01 +0100]: [912C] S: * BYE Logging out
[07-Jun-2013 12:30:01 +0100]: [912C] S: A0003 OK Logout completed.

Login from any other client I've tried works fine (i.e. outlook, iphone)

Is there something I need to change in my config ?

Thanks for any help.