[Dovecot] Dovecot Imap Stopped working

Dovecot has been working fine for months. We are using 1.0. Come in to work today and dovecot quit working POP3 and IMAP. I restarted the service and everything started working except IMAP? We use Dovecot as an authentication method for outgoing mail and it works. I can't telnet to myhostname.com 143, Squirrelmail will NOT work either. Where is a good place to start looking for signs of the problem. When we restart we get no errors, which is strange?

K