samba - Nov 2003 - some win2K machines get "incorrect username/password" error

A recent update was made to our "standard image" for new computers. It
is for win2K.

These new computers cannot connect to a Samba 3 server running a simple
smb.conf.

(Just for the sake of full disclosure, the same exact symptom is happening also
with an old appleshare ip server offering SMB)

The slightly older win2K machines have no problem connecting.

I've been around a little bit with my image guy about setting the
"allow cleartext passwords" bit to be on from the client, but that
doesn't make sense since on the machines that DO work, the cleartext
password bit is set to off.  And my understanding of that setting is only to
allow backward compatibilty for these clients to connect to older servers.

I've been searching the web for days for an answer...looking at log files. 
Seems like I see some common threads about user "nobody" needing to
log in, and I in fact do see errors in the log regarding that, but this happens
both for clients that work and clients that do not work, so it seems like a
blind alley to me.