Windows Longhorn build 4088

Installation

 * As typical of builds in this build range, it tends to take a long time to install and can be unstable.
 * Various commands in WinPE's command prompt such as formatting a drive will not work due to  being missing.
 * Redirections like  do not 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 Themes Setup. To fix the issue, open up Task Manager by pressing Ctrl, then restart 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).
 * During the second stage of Setup, Task Scheduler throws out an error. However, the installation continues normally.

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.

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.
 * 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.

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 appear and 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.
 * 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.
 * The sidebar notifications and system tray doesn’t render correctly.

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 (if present).
 * 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 tends 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 . 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 known to not work on these pre-reset Longhorn componentized builds.

Other bugs

 * The Task Manager in this build has a chance of hanging when launching a new task if Windows Explorer is not running.
 * 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.
 * The color depth is set to 16-bit by default, rather than 32-bit. This also appears in build 4093.
 * The Quick Launch and Classic Tray tiles exhibit an unique bug in this build, as each icon is displayed in a different row.