who would think that Black Mesa Facility was a beta tester for Microsoft .. well, when you install this pack you'll find all Computers in the facility using Windows NT 5.0 Which was The Windows 2000 Beta ... But this beta doesn't seem to be stable and cause the incident in the facility
Information About Windows NT 5.0 Beta (From Wikipedia) :
Windows 2000 is a continuation of the Microsoft Windows NT family of operating systems, replacing Windows NT 4.0. The original name for the operating system was Windows NT 5.0. Beta 1 of NT 5.0 was released in September 1997, followed by Beta 2 in August 1998. On October 27, 1998, Microsoft announced that the name of the final version of the operating system would be Windows 2000, a name which referred to its projected release date. Windows 2000 Beta 3 was released in January 1999. NT 5.0 Beta 1 was similar to NT 4.0, including a very similar themed logo. NT 5.0 Beta 2 introduced a new 'mini' boot screen, and removed the 'dark space' theme in the logo. The NT 5.0 betas had very long startup and shutdown sounds, though these were changed in the early Windows 2000 beta, but during Beta 3, a new piano-made startup and shutdown sounds were made, featured in the final version as well as in Windows ME. The new login prompt from the final version made its first appearance in Beta 3 build 1946 (the first build of Beta 3). The new, updated icons (for My Computer, Recycle Bin etc.) first appeared in Beta 3 build 1976. The Windows 2000 boot screen in the final version first appeared in Beta 3 build 1994. Windows 2000 did not have a codename because, according to Dave Thompson of Windows NT team, "Jim Allchin didn't like codenames".