Windows Longhorn build 4051

Build of Windows Longhorn
Release nameWindows Longhorn Client Preview
OS familyWindows NT
Version number6.0
Build number4051
Architecturex86, x64, IA-64
Build labidx02
Compiled on2003-10-01
Expiration date
Timebomb+180 days after original install date
About dialog
TCB.png TCBGallery.png

Windows Longhorn build 4051 is a Milestone 7 build of Windows Longhorn. It is the build given to attendees of Microsoft's Professional Developers Conference 2003 in Los Angeles, California, held between 27 and 30 October as a cut-down release from the demo builds shown off at that conference, making it one of the only two pre-reset Longhorn builds to receive a widespread release by Microsoft, the other being build 4074. Interestingly enough, some Microsoft online documentation referred to 4051 as the "M6 build" and 4074 as being part of "M7.2".

This build comes in x86, x64 and IA-64 variants. The x64 version is not overly different from the x86 version, but uses the i386 setup process and several apps including Internet Explorer 6 have been optimized for x64 (often, the x86 versions do not run).

This build was compiled in evaluation mode and can be installed on the current date. Attempting to log onto the desktop once the timebomb has been triggered will return the user to the login screen.

Editions and keys[edit | edit source]

Architecture Key


IA-64 P9BT8-6HBG3-GRF29-BM92B-M973D

Setup[edit | edit source]

Although the setup process overall is similar to previous builds of Longhorn, this build cannot be upgraded from a previous build of Longhorn, due to this being a PDC build.

New features, changes, and fixes[edit | edit source]

Installation[edit | edit source]

This build can now be installed from CD boot after being frozen at the boot screen from build 4038 to 4050.

Explorer[edit | edit source]

  • New Documents and Photos and Videos libraries.
  • The prefix "My" was dropped in most of the remaining folders, resulting in new names for locations Computer, Network Places and Contacts.

Internet Explorer[edit | edit source]

Internet Explorer 6.05 included an add-on manager, a download manager, pop-up blocker, and a tool to quickly delete browsing history.

Other new features and changes[edit | edit source]

  • A new TCP/IP stack. IPv6 is also enabled by default in this new stack.
  • Self-Healing NTFS was added in this build.
  • The top buttons in the migration wizard now function.
  • The winver banner has been changed to align with the new Slate theme.

Bugs and quirks[edit | edit source]

Shell[edit | edit source]

The x64 and IA-64 compile of this build lacks the Sidebar and Explorer preview pane as a result of the absence of the Avalon framework, which was still being implemented onto different architectures at the time of compilation. It would eventually be completely ported over and included by default starting with the IA-64 compile of build 4067.

ClearType[edit | edit source]

Some copies of this build's x86 counterpart do not have ClearType font smoothing enabled by default.

Notifications[edit | edit source]

Notifications tend to reappear quite a lot, until the user reaches a certain point where they will finally close for real upon closing. To fix this, disable the Sidebar or click on Options, and then click on "Don't show this again".

TCP/IP stack[edit | edit source]

The TCP/IP stack has a few bugs, however, most of them were fixed in build 4053.

x64 build specifics[edit | edit source]

The x64 compile of this build suffers from performance regressions and is subject to a number of bugs, which also include a crash on startup. The build installs a barebone set of drivers during setup, and additionally lacks a significant majority of the WoW64 compatibility layer, resulting in most x86-based applications not being able to run properly. To achieve better performance, apply the Windows Classic theme.

Hardware Abstraction Layer bugcheck on Checked/Debug compile[edit | edit source]

Attempting to boot the x64 checked/debug version of this build on a host device that has the Hyper-V hypervisor enabled causes an exception within the Hardware Abstraction Layer's processor feature check, in turn triggering a 0x7E (SYSTEM_THREAD_EXCEPTION_NOT_HANDLED) bugcheck. The issue can be worked around by either substituting the hal.dll binary with the variant from the Free compile or by disabling Hyper-V (HypervisorLaunchType) from the host's boot configuration options.

Gallery[edit | edit source]

PDC 2003 discs[edit | edit source]