Entire Network neighbourhood dissappears after refreshing first vi

I have a client with a network with 22 Windows 98SE computers. When they
start up first, and you open "Network Neighbourhood", you can see all the
pc's listed, and all the XP machines, and the "Entire Network" icon.
If I refresh the view, or go into the "Entire Network" icon or one of the
pc's, when I go back, the whole newtork is gone, absolutley nothing.
closing down and reopening network neighbourhood doen't fix it.
The only thing that gets it back is restarting the computer, and ten you
have it only once again, so not really a fix.

I'm sure this is setting somewhere or something I need to add into Win98Se,
but what?

In network properties I have:
Client for MS networks
Dial Up adapter
the Network adapter
File & Printer sharing for MS
TCP//IP
NetBEUI

Is there anything I'm missing?
TCP/IP is using DHCP and works fine, it's just the network browsing. I tried
setting the Master Browser of one of the PC's, but still the same problem.

any solution?

--
MCSE 2000