samba - May 2004 - XP pro can't join Domain

I have been working on a a Linux server (file, printer, & PDC) for the last
6 months. I am currently using Fedora with Samba 3.0 as my server. I have an XP
pro(xppro) and Win 98(winlin) machines on my small network. The file and print
server seems to be working fine on both clients. However, my XP machine is not
joining the the domain.
 
Symptoms:
1.  As I try to join the domain as a "root," I get 

    The following error occured attempting to join the domain <Domain
Name>:
                User name could not be found

   On the 'xppro.log' file it says, "root logged in as admin user
(root privileges)"

2.  As I try to join the domain as me, it says,

   The following error occured attempting to join the domain <Domain
Name>:
                Access is denied. 
 
Here are some of the things I have tried so far. 
 
- changed the registery settings on the XP machine accordingly
- added "root" as a samba user (smbpasswd -a root). The account also
exists in /etc/samba/smbpasswd file.
- my user add script = /usr/sbin/useradd -d /dev/null -g 100 -s /bin/false -M %u
 
I have been trying this for the last 3 days. I have used RedHat 9.0 with samba
2.2. and was able to join the domain from this XP machine.
 
I really need your help!!! I have to get the server ready with BDC and LDAP for
testing under a network containing 30 XP pro and 40 win 98 machines and two
printers.
 
If you need my smb.conf file, I will be happy to provide it!

		
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>From the Howto Collection
30.4.2. Changes in Behavior

2. When adding machines to a Samba-2.2 controlled domain, the ?add user
script? was used
to create the UNIX identity of the Machine Trust Account. Samba-3
introduces a new
?add machine script? that must be specified for this purpose. Samba-3 will
not fall back to
using the ?add user script? in the absence of an ?add machine script?.


Mark