I have a network in my professional office that has been running for years without a problem. We are upgrading our workstations and in the processes, some of them can no longer see the server and vise versa. The server is running Server 2000. There are 9 workstations, 2 of which are running XP Pro and the remaining older ones are running Win98. In the processes of configuring new XP systems to replace the old Win98 systems, our existing XP systems can no longer communicate with the server. This seemed to have happened during the the installation of the new XP Pro systems, which also cannot see the server. There is a Netgear router which connects everything to the internet through a network switch. Again, everything worked fine until attempting to configure the new systems on the existing network. Any ideas?

Make sure that Internet Connection Sharing isn't enabled on one of the new machines. One of the things that I noticed is on some 'generic' setups this somehow got enabled, and was issuing a conflict between DHCP servers. Another way to test this, is to remove the new machines from the switch, and reboot the old machines. Then check to see if you are still experiencing issues.

You may also want to make sure that the machines have all the right network protocols enabled, and make sure that none of your machines have any virus's. Another cause of these type of issues is that one machine will be overloading the switch with traffic, preventing the others from working correctly.

Thank you for your help. I will try those thing.