Windows Neptune build 5086.1

There are 2 files, namely  and   with version number 5.50.5086.1 in Windows Millennium build 2404, but it is unknown whether this Neptune build ever existed.

Some speculate this could be a late Milestone 1 or an early Milestone 2 build. Judging by the file dates, it would have been compiled before 1999-10-26.