samba - Apr 2003 - Can I use winbind to auth against a samba 2.2.7 "PDC"?

I'm looking for a valid way to let users have a single point password change
for windows login and IMAP. As I don't want to resort to clear text
passwords (that would allow to sync the UNIX passwords) I went the other way
that is pam for IMAP (via winbind). It's just that  wbinfo -t says
"Secret
is bad" and wbinfo -a gives a:

plaintext password authentication failed
error code was NT_STATUS_DOMAIN_CONTROLLER_NOT_FOUND (0xc0000233)
Could not authenticate user ... with plaintext password

The NT_STATUS_DOMAIN_CONTROLLER_NOT_FOUND is the most strange one. If I
tcpdump the machine it looks like winbind asks for PDC only at broadcast as
there were no "wins = ..." directive in smb.conf.

Needles to say I've joined the  domain. I can do a smbclient -L PDC and the
response comes instantly. Run out of ideas... Still: is it possible to use
winbind and samba PDC? Or it was designed only for M$ software?