This occurs when NNTP is installed and running, but not actively performing any function - though it's merely not configured, the server seems to think there might be a problem. If you're not actually using this service at present, you might disable it or uninstall it to prevent all those system log entries.".
NNTP is required during Exchange 2000 setup or uninstall. I recommend disabling the service and not uninstalling it. This event (and all the NNTP service messages) can be stopped from being recorded in the event log by stopping the NNTP service. Use Exchange 2000 System Manager to stop the Default NNTP Virtual Server (Navigate to Servers... <server name>... NNTP... Default NNTP Virtual Server, right click and Stop. In the Services applet, configure the Startup type of the Network News Transport Protocol (NNTP) service to "Manual".
about disabling protocols in Exchange 2000.