Windows Longhorn build 4088

Windows Longhorn build 4088 is a Milestone 7 build of Windows Longhorn. Previously only the Preinstallation Environment of this build was available until 13 January 2015 when BetaArchive user Daniel uploaded the full version of this build to the aforementioned site's FTP server.

Changes and fixes

 * This build no longer shows the boot screen upon initializing Preinstallation Environment and Setup. The boot screen when starting setup and WinPE was reused in Windows Vista build 5048.
 * A new version of DWM is included, rewritten in .NET managed code. It can be enabled using the instructions found on the Windows Aero page.
 * WordPad can now be opened again after being broken from builds 4081 to 4087.
 * The shortcuts in the quick launch are now present again on the sidebar and taskbar.
 * The CD/DVD/USB icon image now appears on the Autoplay dialog.

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.
 * Redirections like  don't work correctly.
 * When booting to the desktop for the first time,  will max out 1 CPU core.
 * When booting to the desktop for the first time, Personalized Settings may hang on Theme Setup. To fix, open up Task Manager by pressing  then, going to shutdown and restarting the system. This will reboot the machine to the desktop. Alternatively, you can fix this by terminating   (although this causes the system to enable the Windows Classic Theme).

WinPE

 * On some computers and virtualizers, the WinPE doesn't support the mouse, so you must use the keyboard to navigate the WinPE. This seems to be related to using a PS/2 mouse, as USB mice seems to work fine for the setup.
 * Attempting to use the copy command in WinPE to copy files over from the the CD drive to a formatted Hard Drive, will cause a  BSOD.
 * Various commands in WinPE's command prompt will not work due to  being missing.

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

Timebomb
Unlike other Longhorn builds, it contains a broken timebomb and can be installed on the current date. However, before installation, machine time will still be checked and verified.

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

Explorer

 * CD, DVD and floppy 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.
 * On first boot after Setup, some texts in Explorer and taskbar will appear as empty square symbols. This bug only happens on first boot and will go away after a restart.
 * 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.
 * When launching Computer Management, there is a chance that script errors will be displayed relating to missing registry entries.

Hardware / Drivers

 * This build will randomly access the floppy drive.
 * On some boots, Windows may not detect the CD/DVD drive.
 * 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 the error code.

TCP/IP bug

 * The TCP/IP stack can tend to malfunction, as it will result in a BSOD with the 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 0x7B. This is because the  key, located in    is largely incomplete and missing a lot of entries. Restoring the key from a build with working safe mode enables this build to boot in safe mode, but the display is not initialized properly which leads to no video output (which is seen as a black screen).

Other bugs

 * Task Manager is known to hang when launching a new task.
 * When shutting down, restarting or logging off, there is a chance that the system will refuse to log off and get stuck on the  screen. Should this happen, shut down the system by pressing the power button once. This will trigger the Emergency Shutdown function and shut off the system.