Windows Longhorn build 4090

Windows Longhorn build 4090 (full name: 6.05.4090.0 (private/Lab06_dev_ux(pfortier).040729-1145)) is this is a confirmed milestone 7 build. The build was found on Betaarchive. Traces of this OS were found in the Build Explorer files Explorer_6.05.4085.0_private-Lab06_dev_uxpfortier.040629-1845) in all files except Explorer.exe

Errors And Bugs
When trying to apply files in Windows Longhorn build 4086.Main the OS itself does not work after logging in.

Links
https://www.betaarchive.com/forum/viewtopic.php?p=454601&hilit=longhorn+4092#p454601