This problem occurs because the Mup.sys driver assumes that there must be no more than three file-system filter drivers running at the same time. The Mup.sys driver handles Distributed File System (DFS) file I/O requests. If there are four or more file system filter drivers, the I/O request packet (IRP) location buffer that is pre-allocated by
Mup.sys will overflow. When this occurs, you receive the Stop error that is described in the Symptoms section.
Hotfix information for Windows XP
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. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.
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, contact 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:
http://support.microsoft.com/contactus/?ws=support
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
To apply this hotfix, you must have Windows XP SP2 installed on the computer.
Restart requirement
You must restart the computer after you apply this hotfix.
Hotfix replacement information
This hotfix does not replace any other hotfixes.
File information
The English version of this hotfix has the file attributes (or later file attributes) 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 item in Control Panel.
Registry information
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 How to back up and restore the registry in Windows
On a computer that is running Windows XP with SP3, do not install this hotfix. This hotfix is inclued in Windows XP with SP3.
On a computer that is running Windows XP with SP2, install this hotfix or a service pack that resolves this issue.
After you install this hotfix or Service Pack 3 that includes this fix, modify the
DfsIrpStackSize registry entry. To do this, follow these steps:
Click Start, click Run, type regedit, and then click OK.
Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Mup\Parameters
In the right pane, right-click DfsIrpStackSize, and then click Modify.
Note If the DfsIrpStackSize registry entry does not exist, you must create it. To do this, follow these steps:
On the Edit menu, point to New, and then click DWORD Value.
Type DfsIrpStackSize, and then press ENTER.
In the Base box, click Decimal, type 10 in the Value data box, and then click OK.
Notes
A value of 10 allows for a maximum of eight file system filter drivers.
The default value of the DfsIrpStackSize registry entry is 5. A value of 5 allows for a maximum of three file system filter drivers.
If you set the value to a number that is greater than 10, the value is automatically set back to 5.
If you do not apply this hotfix, the DfsIrpStackSize registry value is ignored.
Exit Registry Editor.
Restart the computer.