Windows Longhorn build 4042 (main)

Windows Longhorn build 4042 (main) is a build of the Windows Longhorn operating system. This build was compiled four days before the Lab06_n compile, and as such, is technically a Milestone 6 build. Prior to its leak, UX.Unleaked had a post with three images from this build. Later on 2020-01-23, this build was listed on a thread by the blog's founder Grabberslasher to be released to the BetaArchive FTP, and was released in the twelfth and final set of his 33 Longhorn/Vista builds on 2020-02-04 along with build 4082, build 4087 and build 5492.

This build still uses the old boot screen and wallpaper from previous Milestone 6 builds, and also continues to use Pig Latin in its build string. As with build 4040, both opaque and transparent Aero Glass options are available via Desktop Composition Engine. Windows Media Player Sidebar tile works and plays .mp3 files, but causes huge CPU usage. It is the last build with the Plex theme.