NT4 -> Win2K3 question

I fail in my last migration due to some of the computers (Windows NT
workstation /w SP6) fail to access Windows 2003 server. Do you have any
idea why? Thanks.

Background
==========
We have total 50 PCs most of them are Windows NT Workstation and the rest is
Windows 2000 in the network. All of them get IP and TCP/IP setting from DC1
DHCP server

We have 2 Win2003 standard edition DCs. DC1 installed DNS integrated with
AD and secure DDNS, WINS and DHCP. DC2 installed DNS integrated with AD and
secure DDNS, WINS and printer server.

We has 6 Windows NT Workstation PCs has problem.

Symptoms
=========
1. Those 6 PCs can get IP from DC1 DHCP server.

2. Those 6 PCs can logon to the domain

3. Those 6 PCs can ping DC1 and DC2.

4. Those 6 PCs can list DC1 & DC2 NetLogon or Sysvol directory even I logon
as domain Administrator. It said Access denied.

5. Those 6 PCs do not run the logon script. I believe it is because those
PCs cannot access DC1/DC2 NetLogon directory

6. After change DNS integrated with AD and secure DDNS, only few PCs name
and IP address show in the zone under Forward Lookup Zone.