Files saved to a mapped network share from Windows XP are corrupted

When you try to save a file from a Microsoft Windows XP-based computer to a network share on a Windows-based server, the saved file may be corrupted. Typically, the saved file contains zeros in the end of the file instead of the expected data.

This problem may occur when you use a program that memory maps a file that is not flagged for write caching, and a set end of file is received from the program. This problem occurs when one of the following conditions is true for the client computer that you use to save the file:

• Microsoft Windows XP Service Pack 2 is installed.
• The hotfix that is described in the following Microsoft Knowledge Base article is installed:
  811169   (http://support.microsoft.com/kb/811169/ ) Update to increase the performance of the Network Redirector

In this scenario, the cache is not flushed before the view of the file is unmapped.

To work around this problem, disable opportunistic locks on the server where you are saving the file. To do this, set the EnableOplocks registry value to "0" in the following registry subkey: To do this, follow these steps:

1. Click Start, click Run, type regedit, and then press ENTER.
2. Locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
3. If the EnableOplocks value is not present in the right pane, you must create it. To do this, follow these steps:
   1. Right-click Parameters in the left pane, point to New, and then click DWORD Value.
   2. Type EnableOplocks to name the value, and then press ENTER.
4. Right-click EnableOplocks, and then click Modify.
5. In the Value data box, type 0, and then press ENTER.
6. Quit Registry Editor.

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. 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: 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.

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 tool in Control Panel.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For additional information, click the following article number to view the article in the Microsoft Knowledge Base: