Microsoft Windows Codename Neptune, 5.5.5111.1


General information
File format
  • Compact Disc
Bootable No
Architecture x86
  • English
  • Consumer

Install information
Full buildtag 5.5.5111.1
BIOS date 12/12/1999
Timebomb 31/10/2001 (+690 days)


The only leaked Neptune build, includes Activity Centers.
This Microsoft project was never released but some features ended up in Windows XP and above.
NTC Stands for NT Consumer.

The screenshots are provided by KenOath.

1st April 2020 release
On the 1st of April 2020 a new disc appeared which is the best version we could possibly see out of Neptune mostly original.

This is the same build that was given out to external testers on 1999/12/27 as the 6th variant.


Enable the Activity Centers
Copy accore.dll to C:\Windows\System32
Run regsvr32 accore.dll from the Run window or Command Prompt.
Right-click the desktop and select Active Desktop --> Show Web Content
Right-click the desktop and deselect Active Desktop --> Show Desktop Icons
Right-click the desktop and select Active Desktop --> New Desktop Item...
Click on Browse and select C:\WINNT\Activity\Start\StartPage\Millennium Desktop.htm
At the top bar click on the arrow down and select Cover Desktop

Screenshots (111)

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