Xp pro client good only connect to one DC in the domain

Hi there,

Got two domain controllers
1) server 2000 sp4
2) server 2003 R2 sp1

Because I am slowly migrating all resources from the old 2000 server to the
new 2003 server, all clients (xp pro) connecting on resources on both domain
controllers.
All clients are working fine, except one of them. All resources on the new
server working fine, but all resources like printers and file sharing on the
old 2000 server does not work at all.
It seems that the client only connect to the new server, but it’s one domain.

error messages in log files on the client are:

There is no domain controller available with the reason there is no RPC
server available.

DCOM got error 'class is not registered ' from Server-2000 by activation
of the server = dcom ID: 10006 error

What good be the reason the client only connect to resources on the new
server??

greetings Nike