Windows XP Explorer Pane flickers on mapped network drives

When you view local drives or mapped network drives in Windows Explorer on a Windows XP-based installation, the left pane (folder tree) or tree view may flicker or constantly refresh the whole directory structure with speeds varying from every few seconds to every few minutes.

Microsoft Windows-based servers continue to communicate file system changes to Windows XP-based clients. This may cause extra traffic over a wide area network (WAN).

These symptoms do typically not occur on Windows 2000 clients.

If you have mapped a drive to a share on a Windows-based server, and changes occur in the file system in the folder tree of the mapped share, the server reports the change to the Windows XP client.

Windows Explorer refreshes or redraws the open window when it receives a file change notification.

Note Excessive flickering can also be caused by antivirus software or some other rogue third-party software constantly updating the folder or directory tree on the server that clients are connected to.

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:
To resolve this problem, apply the Critical Update 810565, and add a new registry key. To do this, download 810565 from the following Windows Update Web site:
After you apply hotfix 330929 or Critical Update 810565, you can add one of the following new keys to the Windows registry to turn off Change Notify requests for file and folder changes that occur in subfolders of a mapped network share:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer

Configure the new key as follows: A setting of 1 turns off Change Notify requests for file and folder changes that occur in subfolders of a mapped network share. When you set this registry key, the server still sends a Change Notify event when a file or folder is changed in the root and first directory level of the mapped network share. However, the server does not send a Change Notify event when a change is made at the level of the second subfolder or deeper in the mapped network share, and therefore you notice less flickering in the tree view of Windows Explorer.

Note When you change the value of this key, this has no impact on the active view of each folder in Windows Explorer. Updates are visible immediately.

When you set the NoRemoteRecursiveEvents key, you may experience the following issue: If systems have redirected USERPROFILE or other network based configurations, the user interface (UI) may not update automatically if this setting is enabled.

Additionally, you can minimize network traffic by implementing a well-structured folder organization on your file servers, as in the following sample structure: The "users" folder in this sample is at folder depth 1 when you map a drive to \\server\sharename.

With this folder structure, most changes to files occur at folder depth 2 or deeper. Therefore, the number of ChangeNotify requests being sent across the WAN is minimized.

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

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:

When you analyze network captures, Network Monitor shows the following excessive SMB Notify Change traffic: In some cases, excessive READ and QUERY INFORMATION requests are performed by Explorer.exe to various Desktop.ini files on the network drive.
A previously released hotfix, 318675 (Shell32.dll and Cscui.dll dated 17-Mar-2002), resolves this issue.

Critical Update 810565 includes all Shell32.dll changes from hotfixes 330929 and 318675.

This flickering may also occur if misconfigured antivirus software is installed on the workstation or on the file server. There are some issues with certain antivirus software if the heuristic scanning or real-time scanning options on a network share are turned on. You may have to disable the ScanNetwork real-time configuration option in the antivirus software that is installed on the client or on the file server.

For troubleshooting purposes, use the following methods in the order that they are presented (as required):

1. Turn off network drive scannning. See the documentation for your antivirus software about how to turn off heuristic scans or real-time scanning on a network share.
2. Disable your antivirus program.
3. Remove the antivirus software on both the client and the file server.

Flickering may also be caused by excessive QUERY_PATH_INFO traffic. In this case you can solve the issue if you download and apply the Hotfix KB834350 and create the InfoCacheLevel registry subkey with a value of 10. For additional information about hotfix 834350, click the following article number to view the article in the Microsoft Knowledge Base: To create the InfoCacheLevel registry subkey, follow these steps:

1. Click Start, click Run, type regedit in the Open: box and then click OK.
2. Locate and click the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MrxSmb\Parameters
3. Click Edit, click New, and then click DWORD Value.
4. Type InfoCacheLevel to replace New Value #1, and then press ENTER.
5. Click the InfoCacheLevel DWORD value in the right pane, click Edit, and then click Modify.
6. Under Value data, type 10, and then click OK.
7. Quit Registry Editor.

Note InfoCacheLevel can have any one of the following values in hexadecimal notation:

• 0 – Disables the caching for all files and folders
• 1 – Enables caching for files with short file names (8.3) – default
• 10 – Enables caching for all files and folders