server manager problem

I have a pdc on Win NT 4 sp5 that is the primary WINS server for the domain, the problem is that when server manager is opened all the computers on the domian are greyed out and it can’t tell which type of machines are out there. Some other facts.This happened before and in Net neighborhood all you could see were the pdc and bdc. The problem was the same with the pdc saying each computer was “nt 4 workstation or server” and the pdc and bdc were recognized as servers. Last time I rebooted and it came back. This time no dice. The pdc is still functioning and I can see all the cpus on the domain from a workstation. Any thoughts, I am kind of stumped.