Windows Longhorn build 4074

Windows Longhorn build 4074 is a Milestone 7 build of Windows Longhorn that was leaked in May 2004. This build is the official WinHEC 2004 preview build.

Setup
Setup overall is mostly similar to previous builds of Longhorn.

Features
Many features that were present in earlier builds have been removed or hidden in this build. As a result, the features that remained were improved:


 * This is the first build to use the Segoe UI font as its default font, which was also found in later operating systems.
 * Many of the icons were replaced with new, more modern icons, such as the My Computer and Internet Explorer icons.
 * The user profile picture has been replaced with a grey variant.
 * While the Slate theme is still present, it also contains the new Jade theme that is also present in build 4066. The default wallpaper has also been changed to "Leaves". The Jade theme also enables native Aero transparency, which has not been seen since build 4042 (however, full transparency will require you to put on the Desktop Window Manager and have the window small; if the window is maximized, then it will be opaque, like in Windows Vista RTM).
 * This build, unlike many other leaked builds, is the first build to have complete Aero effects in Explorer and Internet Explorer from the Desktop Window Manager, thanks to an early version of MILExplorer. However, a registry modification is required to extend the effect into the full UI of Explorer and Internet Explorer. The green translucent effect is used natively in this build instead of transparent "Glass". Further modification (such as a modified version of the build such as TWIWMTB (Longhorn The Way It Was Meant To Be) or a patched  file) is required to replace the translucent borders with glass. On how to enable Aero transparency, go here.
 * This build also contains Aero Stars, an animated desktop which shows stars bouncing around the screen. It is somewhat buggy, and some graphic adapters may have trouble rendering it.
 * This build has the preview and filter panes improved, especially the Preview Pane, which is more functional than its leaked server counterpart, build 4066.
 * This build contains an Animated Preview Pane Aurora, but requires some modification to enable it.
 * MSN Messenger has been updated to version 6.1, with a completely new interface.
 * This build contains numerous updates to general prompts, ranging from the Autorun prompts to "not responding" dialogs.
 * A new driver installation system is implemented. As a result, most drivers that worked on Windows XP will often have the driver installation fallback to a "pre-release mechanism" upon installation. If you get a pop-up notifying about the pre-release mechanism, simply press cancel.
 * IIS has been updated, but in Windows Components Wizard it says IIS 7.0; after installation it claims to be version 6.5.
 * Libraries have been updated and now have a majorly uplifted banner.
 * The IA64 compile has complete .Net and Avalon support.

Do note the features related to .NET Framework, such as the sidebar, full Aero or Aurora, don't work on the amd64 version. Basic DWM functionality is present, but can only be enabled by directly calling relevant uxdesk.dll exports, because sbctl.exe is missing.

Bugs and quirks

 * This build cannot be upgraded from a previous build, and can only be clean installed.
 * This build can be installed on the current date.
 * The Checked/Debug compile of the x64 version has an assertion error in the IDE driver that results in a BSOD during "Completing installation" phase with an error code of 0x1E and 0xFFFFFFFF80000003 as there were no kernel debugger attached at that point. When this occurs, start WinDbg on the host, connect the debugger to the VM's virtual serial port (shut down the VM then add and configure one if there are none in your VM), then restart the VM and press the F8 key to select "Debugging Mode" and continue the setup. Once the "Assertion failed" message appears, type "ignore" or the letter I to the debugger command window. Repeat this on every message until the setup finishes.
 * Resizing the taskbar does not work, as it will only stay at one size.

Themes
Upon changing themes, three are a few bugs you can encounter. One of which is the services theme can malfunction, causing the taskbar to have the classic theme visuals, and the start menu possibly being entirely black. This is generally easy to fix, however, since all it requires is restarting the Themes and Desktop Manager service in services.msc. Another issue, which is more likely, is Explorer failing to render entirely. If possible, initialize the CTRL+ALT+DEL sequence and open Task Manager to terminate explorer.exe, otherwise you're only left with restarting the system.

No mouse driver in WinPE
On some computers and emulators, the mouse does not work in the WinPE for this build and subsequent builds. If the mouse doesn't work, 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.

Creating folders
The option to create folders by right-clicking and selecting New doesn't work as the Folder entry is hidden. However, several unofficial patches have been created to address this issue. Also, folder creation may be enabled by applying the following registry key: Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\.Folder]

@="Folder"

Memory leak
As with most later Longhorn builds, this build's Explorer tends to leak memory after a while. Turning off the Sidebar reduces the effect of the memory leak.

Faulty file browse UI
The main File Browse UI has two noticeable bugs. The first being that the Navigation Bar only allows for navigation by clicking on parent directories in the bar. The second being that the Filter and Preview panes may occasionally appear black or show parts of content behind the window.

Safe mode
This build has a glitch with the Explorer Safe Mode desktop prompt. The prompt will appear titled "Desktop" and will ask to proceed to work in safe mode or to System Recovery. Clicking either button will hardly perform any action and will bring up another exact prompt. The desktop will not appear with the prompt and Explorer may not launch. It is possible to fix safe mode with a registry modification or instructions below to use the Explorer shell in Safe Mode normally. Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Sidebar]

"Enabled"=dword:00000000

How to fix the safe mode bug:
1. Start in Safe Mode with Command Prompt.

2. Type in  in the Command Prompt window.

3. Navigate to.

4. Create a DWORD (32-bit value), name it Enabled, set it to 0, and then close Registry Editor.

5. Type in explorer in the Command Prompt window, once done, Windows Explorer will now start in Safe Mode.