This build is known for containing a file from Microsoft NepTune. One file (gemstar.sys) is versioned 5.50.5067.1 and branded Microsoft (R) Neptune(TM) Operating System. Microsoft NepTune was going to be the consumer successor of Windows 98 and NT successor of Windows NT 5.0 at the time (which was later renamed to Windows 2000), which explains why. Windows ME was made up at the last second and was the last 9x release by Microsoft.
