Windows NT 4.0 build 1166

Windows NT 4.0 build 1166.1 is a build of Windows NT 4.0. It removes some of the Windows NT 3.x programs, updates the Start menu banner from "Windows NT Explorer" to "Windows NT Server" and has updated NT Diagnosis, but most of the Microsoft Mail application is broken.

The Workstation edition of this build was apparently also scene leaked at the time and was later found on 13 January 2021.