When you install Service Pack (SP) 4 on a Windows 2000-based computer that has DFS Client turned off, you may receive the following stop error message on a blue screen:
Note The parameters may vary.

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This error occurs because of an issue in Mup.sys, but the behavior only occurs if DFS Client is turned off. (By default, DFS Client is turned on in Windows 2000.) This error only occurs if DFS Client is manually turned off or if another program has turned DFS Client off.

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Hotfix Information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

Windows 2000 SP3 is required.

Restart Requirement

You must restart your computer after you apply this hotfix.

Hotfix Replacement Information

This hotfix does not replace any other hotfixes.

File Information

The English version of this fix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

   Date         Time   Version            Size    File name
   ---------------------------------------------------------
   11-Jul-2003  18:57  5.0.2195.6774      88,624  Mup.sys

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Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

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If you plan to upgrade to Windows 2000 SP4 and you have DFS Client turned off, Microsoft recommends that you perform one of the following procedures before you upgrade:

•	Install the Mup.sys fix, and then turn on DFS Client. -or-
•	If you want to keep DFS Client turned off, apply the Mup.sys hotfix to SP3.

For additional information about how hotfix packages are named, click the following article number to view the article in the Microsoft Knowledge Base:
If you have DFS Client turned off when you apply SP4, and then you restart the computer without first applying this hotfix, you may receive the stop 0x1E error message, and you may not be able to start the computer.

When this error occurs, use either of the following methods to resolve the problem.

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Method 1 – Use the Recovery Console 1. Start the computer by using the Recovery Console. For additional information about how to do this, click the following article number to view the article in the Microsoft Knowledge Base: 216417 (http://support.microsoft.com/kb/216417/EN-US/) HOW TO: Install the Windows Recovery Console 2. Open the SP4 uninstall folder. By default, the SP4 uninstall folder is in the following location: %SystemRoot%\$NTServicePackUninstall$ 3. Copy the Mup.sys file from the SP4 uninstall folder to the following folder: %SystemRoot%\System32\Drivers 4. Restart the computer. 5. Install the hotfix that is described in this article. 6. Restart the computer.

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Method 2 – Use Registry Editor to Turn on DFS Client Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: 322756 (http://support.microsoft.com/kb/322756/) How to back up and restore the registry in Windows To turn on DFS Client by editing the registry, follow these steps: 1. Click Start, click Run, type regedit in the Open box, and then click OK. 2. Locate and then click the following key in the registry: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Mup 3. Right-click the DisableDfs value, and then click Modify. 4. In the Value data box, type 0, and then click OK. 5. Quit Registry Editor. The DisableDfs registry value uses the following settings: DisableDFS: REG_DWORD: range: 0 or 1 0 = enabled; 1 = disabled Default: 0 Make sure that the value is set to 0 to turn on DFS Client.

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