Workgroup clients can access domain shares`

I have a sbs 2003 running DHCP. The Guest account has been disabled. I verified this by the net user guest command.

All share permissions seem to be working fine within the Domain and the Everyone group is not listed. I have one NT machine that is on a Workgroup and gets its IP from the sbs server. It has access to all shares with no apparent restrictions.

Any ideas or direction would be great.