Windows Longhorn build 4050 (idx02)

Build of Windows Longhorn
OS familyWindows NT
Version number6.0
Build number4050
Build labidx02
Compiled on2003-09-28
Expiration date
Timebomb+180 days after original install date
Home Edition
Product key
About dialog

Windows Longhorn build 4050 (idx02) 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 later released in the fifth set of his 33 Longhorn/Vista builds on 28 January 2020 as a checked/debug build alongside build 4085 (Lab07_N).[1] It is the second publicly available Home Edition pre-reset build of Longhorn.

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.

Setup[edit | edit source]

Although setup is mostly the same as the previous build of Windows Longhorn, a new Slate-styled background is used.

Changes[edit | edit source]

Login screen[edit | edit source]

  • The login screen has changed once again, now it is transparent as it does not have a background. This is because, in these builds, the "SYSTEM" user account does not have a default wallpaper. This change was most likely done to in order to let OEMs put a logon background with their logos.[2]
  • The Windows logo upon logging in now comes up instead of coming down.

ClearType[edit | edit source]

ClearType is enabled by default again, after being disabled in Lab06_n compile of build 4042. This would persist up to build 4074.

Bugs and quirks[edit | edit source]

winver dialog[edit | edit source]

This build uses the older winver banner first seen in build 4005 instead of the new one from build 4044, likely because the change did not make into Home Edition at that time.

Installation[edit | edit source]

  • This build cannot be installed normally due to an assertion failure in AGP440.SYS, thus resulting in a 0x0000007E (SYSTEM_THREAD_EXCEPTION_NOT_HANDLED) bugcheck when booting into the second stage of setup. To bypass this issue, set up kernel-mode debugging with WinDbg to ignore the failure[3] or replace drivers with ones from the non-checked/debug compile of build 4051. This error does not happen on real hardware and on 86Box machines that don't have an AGP slot.
  • When booting into the second stage of setup, the system will play a long beep on systems that have a PC speaker.
  • Due to this build being a PDC build like build 4051, this build cannot be normally upgraded from a previous build and can only be clean installed.

Gallery[edit | edit source]

References[edit | edit source]

  1. grabberslasher. New Longhorn Builds for a New Decade, BetaArchive. 23 January 2020.
  2. Googulator. Why did Microsoft replace the blueish Login background from 4042 to the black one from 4074, BetaArchive. 25 November 2021.
  3. [Guide] Install Longhorn 4051 x64 chk, BetaArchive. 20 December 2012.