POP3 problem

Does anyone have any ideas why I am unable to retrive mail via POPs from my RH9 server. For whatever reason the server rejects the login credentials. IMAP is installed and the POP3 daemon is running and listening on port 110 (verified by telnetting). I’ve tried Outlook 2000, Express and Thunderbird from Win XP client. I also tried Evolution on the mail server with the same result (ERR – bad login). This occurs with all users and the passwords are correct. I’ve also tried this on another similar server with the same results. Firewall services are turned off. Any ideas?