Windows Longhorn build 4087

Windows Longhorn build 4087 is a Milestone 7 build of Windows Longhorn. On 23 January 2020, this build was listed on a thread by UX.Unleaked blog founder Grabberslasher to be released to the BetaArchive FTP, and was released in the twelfth and final set of his 33 Longhorn/Vista builds on 4 February 2020 along with the main compile of 4042, build 4082 and build 5492.

Changes

 * The setup text during the setup and hardware portions has been changed in this build.
 * The program crash dialog (non-Avalon programs) now has a Cancel button and a choice to debug the program by clicking on the Cancel button.

Installation

 * As typical of builds in this build range, it tends to take a long time to install and can be unstable.
 * Partition and format a drive from a previous or later build prior to starting installation.

No mouse driver in WinPE
The mouse driver in this build's WinPE does not function on specific hardware configurations or hypervisors, and may require a keyboard to navigate through the installation procedure. This issue appears to be largely related to using a PS/2 mouse, as most ordinary USB mice appear to function properly in setup.

Upgrade
Attempting to upgrade from other builds is not possible as one of two outcomes may occur:
 * 1) A bugcheck with error code 0x7E after the second reboot. This is commonly observed when trying to upgrade from non-componentized builds, such as 4074 (via a registry tweak that reports it as a componentized build).
 * 2) An error during the file copy phase.

WordPad
WordPad does not start, as it will display with  instead.

Outlook Express
Outlook Express does not start due to registry errors and certain dependencies on WinFS.

Themes
The Windows Classic theme does not function due to a broken  file.

Explorer

 * CD and DVD drives behave like local disks.
 * Help and Support crashes Explorer.
 * Explorer will crash after adding the display tile in sidebar and won't launch again. A workaround is to create a new account via cmd.
 * When the Aero taskbar and sidebar are enabled, the Taskbar erroneously uses the Sidebar background.

Control Panel

 * Hardware and Devices folder does not open.
 * By default, the Phone and Modem Options Control Panel applet name is empty.
 * Computer Management displays script errors due to missing registry entries.

Graphics
On some computers, you will need to enable VGA Mode after installing video drivers or the system will result in a blue screen of death with a error code.

Windows Product Activation
Windows Product Activation is missing.

Safe mode
The Safe mode is completely broken and results in a bugcheck with code. This is because the  key, located in    is largely incomplete and missing a lot of entries. Restoring the key from an earlier build with working safe mode allows this build to boot properly, but the video driver will not initialize properly. As a result, the operating system will freeze as it transitions into graphical mode, so Safe Mode is currently not known to work on these pre-reset Longhorn componentized builds.