You've moved a Web server and it now has a different IP address, and users are calling the help desk because they...
can't find it.
Windows 2000 caches the DNS entry at the client level, and until that item expires, users won't be able to learn the new address.
The cure is simple. On the client machine, have the user select Start, Run, and then type in "ipconfig /flushdns" to clear the local cache.