[Samba] Did I screw up my PDC on this Terminal Services problem?

[MargoAndTodd]

Hi All,

I am upgrading my samba server from a workgroup
to PDC server.  I am doing this to make a
Windows 2008 Terminal server happy.  Eventually
there will be a bank of them (thank you Virtual Box).

Anyway, in my test bed, I have a Samba PDC (newly
updated to PDC), a Windows 2008 server, and
XP-Pro-SP3.

Both Windows machines are able to join the domain
and log in as users only in the Samba database.
Both Windows machines have "$" machine names in
the samba database and /etc/passwd.

Problem: the XP machine can only run a TS *.rdp
program on the 2008 server if it logs in
as "administrator".  (I made a *.rdp out of the
calculator program.)

This is why I think I may has screwed up my new PDC.
This is the error log on the 2008 server when a regular
user tries to run the same TS *.rdp program:

Oh crap, I did not get a copy of the error report.
If I remember correctly, it said the user's SID was NULL.

Did I screw up my PDC or is this a Terminal Services
issue?

Many thanks,
-T