The PCs that are having trouble are Window XP and Windows 2000 Pro versions. The domain names associated with the NICs are correct. The IP addresses are unique. Also, they do have unique machine names.
Would it do any good to delete the user and machine names on the Linux server and rebuild them.
I found an IP issue with two PCs. Due to a couple of PCs that were still polling DHCP while the others had static IPs. Due to the power outage the DHCP server in the router restarted.... ? So, I've fixed that from happening again.
Anyway, I fixed the IP addresses in two PCs and they are now all better. It also seemed to fix a third which is now working. Unfortunately, there are two others that are still grumpy and not seeing the domain.
Any ideas. I've reinstalled the network card and drivers. Set the IP address to be unique! And they are still complaining of "A duplicate name on the network".