roundcube problem

[nwmsocal]

I recently downloaded and installed Roundcube on my server and while going through the install process everything is set up correctly and initially I can  log into Roundcube and everything is fine. But a while later my login fails and and I can no longer login. I am running Postfix with Dovecot and both work fine with other clients. I have tried both the stable and beta versions but I still get this same error-

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[09-Dec-2011 02:25:38 -0800]: IMAP Error: Login failed for [email protected] from 175.56.33.233. AUTHENTICATE PLAIN: Authentication failed. in /var$n /var/www/roundcube/program/include/rcube_imap.php on line 205 (POST /?_task=login&_action=login)

[SKaero]

It looks like your mail server doesn't support PLAIN authentication, you'll need to change the authentication to a type thats supported by your mail server.