Service Control Manager (NT4 Wks)

System Event Notification service is failing to start because (according to Control Panel Services Applet) a dependent service has either been deleted/removed or marked for deletion.
Event log states that System Event Notification service will not start because a dependent service: Event does not exist. Apparently I need to reinstall the service (executable?) that is no longer there.

Where can I find the dependent service (executable?) for re-installation?