[Samba] Adding Users to Samba Kill Access

[Jeff]

I've been running two samba servers on a network having a bunch of XP Home
boxes. I recently added an XP Pro box, and wanted to set samba to grant and
deny access, etc., based on users. I've figured out (using webmin) how to
add Unix users to the samba box and how to convert those users to samba
users. 

The weird thing is, when I add users to samba, none of my XP Home boxes can
access the samba shares. I get an "access denied . . .you may not have
permission" (or something like that) message. As soon as I delete all my
users from samba, leaving only "nobody", everything is peachy. 
 
I'd love some help, if anyone has any idea where I might begin debugging
this.

TIA

- Jeff