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 the Activity Centers, a new login interface and user management application, an early version of Internet Explorer 5.5, as well as the new Help Center from Windows ME and several other improvements. 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.

Original disc
In 2011, a person with the nick iapx432 revealed they have the original disc of this build. The contents of the disc were reportedly the same as the leaked copy of 5111.1, but it was revealed that the original volume label of the disc was "NEPTUNE M2", suggesting that 5111.1 is a milestone 2 build. A photo of the disc can be seen in the gallery below.

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, it's actually another HTML application. It's located in, with some of the functionality in. This same login screen was later used in Whistler build 2211, but scrapped soon after 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.

Windows Identities
This is the new user management control panel applet in, also an HTML application. While the old control panel applet is still present initially, it will be removed by the login screen code after the computer restarts. This application is functionally very similar to its counterpart in Windows XP.

Neptune defines four account type:
 * Owner - This type of account is intended for people who can make system-wide changes to the computer. A person with an Owner account can make changes to all Windows accounts that have been created for this computer, such as changing account names, pictures, passwords, and account types.
 * Adult - This type of account is intended for people who can make standard changes to the computer, such as installing applications and software.
 * Child - This type of account is intended for children whose activity should be monitored and who should be safeguarded against corrupting computer settings and deleting important system files. Restricted accounts have limited access to internet content and can have limited computer time. A person with a child account can only change his or her own account name and picture.
 * Guest - This type of account is intended for Guests to use the computer. Guest accounts have restricted access to this computer. Settings, Themes and web browsing history will be erased each time a person with a guest account turns off the computer. Only Documents created by a guest person will be saved.

Help and Support / PCHealth
Help and Support (previously called Help Center) has only loose ties to other Activity Centers, as it's actually stored separately from them in  and is built on top of the PCHealth framework. It appears to have been ported directly from a build of Windows ME, because it still contains many references to Windows Millennium. Despite the presence of this new Help Center, the old Windows 2000 Help application can still be accessed from the Start menu's Help option, although a link to it has been commented out in the new Help Center homepage. There is a broken link to the System Restore executable, which is not present in this build; it's unclear whether Neptune was to include this feature eventually or not.

Available support topics are stored in a Microsoft Access database file called  in. The whole program was designed so that the database can be updated, possibly from online sources, using the  program and   MS Cabinet archive.

PCHealth is set to run at every startup and check the minidump directory for new minidumps after system crashes. If it detects such an event, it will prompt the user to submit relevant information to Microsoft for analysis.

The Bug Reporting page can be accessed either through Help Center or its dedicated desktop shortcut. It's stored in  before it's installed. Although it's from Windows ME, it was adapted for Neptune. The string at the bottom of the page is "Bug Reporting Page Version 5.00.00.5112", and bug reports are saved to   by default. The Bug Reporting page contains two hidden sections with instructions for submitting additional files, one for DirectX and one for System Restore.

Windows Update Auto Update
Another HTML application shared between Millennium and Neptune. It was meant to facilitate automatic updates via Windows Update, but doesn't seem to be working yet. The initial dialog will only be shown on the first run. Auto Update version in this build is 5.4.284.1, and it is located in the  directory. The main executable is, while the HTML UI components are in.

Fast boot
Fast boot is a new feature presumably designed to speed up system boot time. It's contained in  and installed as a service. It can be enabled in the Power options, but only if Neptune is installed on a FAT partition. On the next boot, Neptune will display a window saying "Optimizing boot". At some point it creates a roughly 2-2.5 MB large file named  in the   folder. The image appears to contain the initial memory snapshot of boot drivers and the kernel. The specifics of how this helps speed up the boot process remain unclear.

Internal strings call this "Profile Assisted Boot Accelerator" or "PABA". , the Disk Performance Driver, has also been extended to support this feature.

Prefetcher
This build is the first to have the Prefetcher feature which was later introduced by Windows XP. It's meant to speed up system boot and application loading time by caching the required files. .PF files are stored in the  folder. Prefetcher is enabled by default; to disable it, create a new DWORD value named  in   and set it to 1, then restart the system.

Net crawler
Net crawler was introduced in Windows ME and then ported to Neptune. It automatically searches the local network for shared folders and printers, and then creates shortcuts for them in the My Network Places folder. This feature is enabled by default in this build, but can be disabled by checking the "Disable auto browse for shared folders and printers" checkbox in the advanced folder view options.

Firewall
There is a checkbox to "Enable Firewall mode for this connection" on every network connection's Sharing options page, which suggests a firewall feature of some sort may have been planned for Neptune. It doesn't appear to be functional, though. A built-in firewall was later included with Windows XP.

Submit a comment
Also a first appearance in this build is the "Comments?" link in the title bar of most dialog windows. Clicking it brings up a feedback dialog from  with a brief form to explain the problem. This would then be sent anonymously, along with a screenshot of the offending window, to Microsoft.

Setup
is found on the CD (it is not copied to the hard disk by setup) and appears to be some kind of new setup for Neptune; perhaps it would obtain the installation files from a Microsoft server and install them. Strings inside this file also suggest it may be part of an unattended setup. The program will only run once and doesn't seem to do anything after the window closes, no matter which button you click.

and  setup libraries also contain two extra dialogs, one of which has a placeholder string saying "Files for Neptune build 5XXX are now available.". This suggests Microsoft intended to serve updated Neptune builds similarly to how Windows Update works.

Neptune Credential Manager
appears to be the precursor to the Credentials Manager from later versions of Windows, meant for managing various user credentials in one place. It's described as an "internal Microsoft tool" in the UI, while the file description says "Neptune-to-Neptune Upgrade".

Joindom
is set to run at first login and is used to create the first user account. It's described as a "pre-release Microsoft utility" in the UI, several strings inside this file suggest it's part of the out-of-the-box experience (OOBE), while the file description says "Neptune-to-Neptune Upgrade".

My Pictures Slideshow screensaver
This new screensaver first appeared in Windows ME build 2394, and was ported to Neptune sometime after that. It plays a slideshow of the pictures in the My Pictures folder as the screensaver.

Neptune Server
This build includes the "Configure my server" wizard from Windows 2000 Server editions, which is rather unusual for home and professional editions. An interesting fact about this particular component is that it's also an HTML application. Also included is, another Server component not present in Windows 2000 Professional.

There are also several "Neptune Server" strings inside several setup files, though this could simply be the result of a mass rebranding effort. Although multiple SKUs are defined in the anti-trust documents, it's not entirely clear whether Neptune would also include a server edition.

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

Still Image Service
The Still Image Service is broken in this build and will fail to start. Because it's set to start automatically by default, it causes 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.

Attempting to open the new "Scanners and Cameras" Control Panel folder will fail for the same reason, hanging the Explorer window in the process.

Updating Internet Explorer
Updating Internet Explorer on this build is not recommended, as it tends to break the HTML applications, especially the new login screen, which renders 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.