Windows Longhorn build 4051

Windows Longhorn build 4051 is a Milestone 7 build of the Microsoft Windows "Longhorn" operating system and is also the build given to attendees of Professional Developers Conference of 2003. It was leaked on 2003-10-20.

This Milestone 7 build was distributed at PDC 2003 in Los Angeles, California. This build, for its Professional version, has a x86 and a x64 version. The x64 version is not overly different from the x86 version, but it has a new setup style and several apps including Internet Explorer 6 have been optimized for x64 (often, the x86 ones do not run).

The Check/Debug version was not known to run; it will simply refuse to copy files. However, BetaArchive Discord user WindowsNeptune found a fix to the x64 version, by changing the "/nodebug" tag in the  to "/debug" and installing on an AMD machine.

Features

 * The setup is updated to a Slate interface. Likewise, the login screen has been updated to have a black background and the "winver" banner has been updated.
 * 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.
 * If the Windows Sidebar is enabled in the x86 version, the word "Start" is removed from the Start button (similar to the Start Orb later builds of Windows Vista), leaving only the Windows flag. The x64 version lacks the sidebar completely.
 * Internet Explorer 6.05 included an add-on manager, a download manager, pop-up blocker, and a tool to quickly delete browsing history.
 * Only the basic sidebar tiles are included: Classic Tray, Clock, Quick Launch, Slide Show and Sync.
 * A new TCPI/IP stack. This has a few bugs, however, which were fixed in 4053. Ipv6 is also enabled by default in this new stack.