When you use File and Printer sharing on a Workgroup you tend to find that most of the traffic it creates on the Network is NetBIOS. This has a tendancy to be very messy, and very noisey, especially as your network grows (in part this is why it's not really recommended to have a Peer-To-Peer workgroup with more than 10 PCs).
For example, if one of your clients wants to get the IP Address for your Server Name it will send a network broadcast out to everything on the network and sit there waiting for a response.
It is possible, in certain situations, that without a WINS server you find that you get too much traffic over your network. This can, again in certain situations, overload your switches and hubs and stop them responding for a while. Not exactly a desirable response.
The idea behind a WINS Server (Windows Internet Naming Service) is that instead of it yelling on the network all the time you give it a server which knows as many of the names and IPs as it can.
All you need to do to set it up is add it to your 2000 Server from Add/Remove Windows Components (under Add/Remove Programs), then just make sure all your network clients use it in their TCP/IP Configuration (Advanced button).
One additional change that may help is if you add a registry key so that your 2000 Server always wins those browser elections. Go to this Registry key on the server:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\Browser\Parameters
Then add:
Name: IsDomainMaster
Value: True
Type: Reg_SZ
This is a bit of a long shot really, I'm not sure at all this is causing your problems, but you'd had no response and I felt it was worth a try.