Windows Neptune build 5111

Windows Neptune build 5111.1 is a Milestone 2 build of Windows Neptune. As of 2020, it is the only leaked build of Windows Neptune. It's also known as "Microsoft Neptune Developer Release" and was sent to developers on 1999-12-27. Much of the branding (including Winver) still says "Windows 2000". Although many files have the version "5.50.5111.1", the OS reports "5.00.5111.1" in the UI.

This build cannot be upgraded from an earlier build, only a clean install can be performed. It includes Activity Centers, a new login interface, and changes to Help and Support and certain Control Panel programs. It's set to hibernate by default.

Multiple different copies
There have been several different disc images available online over the years, and most have been modified in various ways, for example to disable the timebomb. The copy currently on BetaArchive was made from the original PWA warez leak from 2000-01 and doesn't feature any modifications, and as such doesn't require a product key but has an active 444 day timebomb.

Activity Centers
Although this build includes the Activity Centers, they are largely broken or incomplete. Several members of the community have attempted to fix or recreate them over the years, with varying degrees of success.

The three main Activity Centers (Photo Center, Music Center and Game Center) and the Start Page are located primarily in, which needs to be registered to install the Activity Centers. You do this by copying the file from the CD to  and running. Once this is done, the files are located in. The Start Page can then be used as the Active desktop page.

The executables for the above mentioned centers are missing in this build, so the default links to them don't work. It's possible to open the individual centers with  instead.

Login screen
Although the new login screen is functionally identical to the one introduced later in Windows XP, but is actually another HTML application. It's located in  and installed by default. This same login screen was later used in Whistler build 2211, but was later scrapped in favour of a DirectUI-based one.

The power button in the bottom left corner will initiate a hibernation by default. To restart the computer, hold down the SHIFT key before clicking the button. To fully shutdown the computer, hold down the CTRL key before clicking the button.

Still Image Service
The Still Image Service is broken in this build and will fail to start. Because it's set to start automatically, it will cause a delay when Windows Explorer is loading. This can be prevented by setting the startup type to either "Manual" or "Disabled" to prevent the service from starting automatically and causing problems.

Attempting to open the new "Scanners and Cameras" Control Panel folder will fail for the same reason.

VirtualBox IDE bug
Like many late builds of Windows 2000, this build also suffers from the IDE bug in VirtualBox and requires the workaround to be applied before installation to prevent it.

Internet Explorer update
Updating Internet Explorer on this build is not recommended, as it tends to break the HTML applications, including the login screen, and thus rendering the build unusable.

Hibernation and ACPI
As mentioned at the start, this build is configured to hibernate by default, which requires working ACPI. If ACPI is not supported or properly implemented on the (virtual) machine, attempting to hibernate may result in either a non-ACPI shutdown or a restart. Shutting down can also result in a restart instead.