Windows Neptune Build 5111

Windows Neptune was a canceled version of Windows 2000 oriented towards the home market. It had featured elements brought over from Windows ME as well as new concepts such as activity centers. No final release of Neptune shipped and most work was rolled into Whistler


Release notes

Build 5111 is the only leaked build which was titled the Microsoft Neptune Developer Release and has a version number of 5.5.5111 (which Windows XP and 2003, 5.1 and 5.2 respectively will see as a newer version).

The login screen was overhauled and had a friendlier full-screen version similar to what shipped with XP, however in Neptune the login screen is an HTA (Hypertext Application - a.k.a. HTML and JavaScript) and not based on DirectUI. Installing IE 6.0 on this build may cause the login screen to cease functioning. Users can have account pictures attached just like in XP. The login screen was improved upon and included in later builds of Whistler (such as 2211).

Neptune allowed for additional account types: Owner, Adult, Child and Guest. The Child account type had safeguards such as Internet content filtering and limited access time. Control of user accounts was through the Windows Identities control panel and was again an HTA.

The help and support center was directly brought over from Windows ME and much of the Millennium branding remains.

Installation instructions

Use a BIOS date of December 11, 1999.

Windows Neptune is slow to load after logon due to a misbehaving service.

Product type
Release date
Sat Dec 11 1999
End of life date
Wed Oct 31 2001
Minimum CPU
P5 133Mhz+
Minimum RAM
Minimum free disk space
User interface
Download count
11 (11 for release)


Download name Version Language Architecture File size Downloads
Build 5111 5.5.5111 Prerelease English 224.07MB 11


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