cyrus-sasl, postfix, courier, mysql: imap working, pop3 not

[snackaugust at arcor.de]

Hey everyone,

hope someone is listening and kind to help some stupid who changed a 
running system. :-)
I believe I have installed the system a couple of months ago following 
this or a similiar guide - not sure:
http://www.phparchitecture.com/howto_show.php?id=2

It used to run until yesterday. Yesterday I fumbled around a bit to get 
rid of some annoying messages about not working TLS.
I never used SSL with POP3 or IMAP, so I started to look for the 
config-files to disable TLS. It went wrong somehow. I now can check 
mails via Imap, but Pop3 doesn' work any longer. Unfortunately, I don't 
have any idea where to start. Maybe someone could help.

All I get is the following message in /var/log/mail:
Nov 22 14:50:03 hellevent pop3d: LOGIN FAILED, ip=[::ffff:213.54.213.156]

I've checked the Mysql-Query-Log: no access to any table from anyone.

What can I try to see what's wrong?
Thanks lot in advance.