How to temporarily deactivate the kernel mode filter driver in Windows

This article describes how to deactivate the kernel mode filter driver without removing the corresponding software. You may want to deactivate the filter driver when you are troubleshooting the following issues:

• File copy or backup problems.
• Program errors that occur when you are opening files from network drives or you are saving files to network drives. For additional information about these program errors, click the following article number to view the article in the Microsoft Knowledge Base:
  814112  (http://support.microsoft.com/kb/814112/ ) Files on network shares open slowly or read-only or you receive an error message
• Event ID 2022 errors messages that occur in the System log, for example:

  Event ID: 2022
  Source: SRV
  Type: Error
  Description: The server was unable to find a free connection number times in the last number seconds.

When you are troubleshooting any one of these issues, frequently, you have to do more than just stop or disable the services that are associated with the software. Even if you disable the software component, the filter driver is still loaded when you restart the computer. You may be forced to remove a software component to find the cause of an issue. As an alternative to removing the software component, you can stop the relevant services and disable the corresponding filter drivers in the registry. For example, if you prevent antivirus software from scanning or filtering files on your computer, you must also disable the corresponding filter drivers.

To disable filter drivers, you must first identify third-party services and their corresponding filter drivers. After you do this, follow these steps.

Warning This workaround may make your computer or your network more vulnerable to attack by malicious users or by malicious software such as viruses. We do not recommend this workaround but are providing this information so that you can implement this workaround at your own discretion. Use this workaround at your own risk.

Important An antivirus program is designed to help protect your computer from viruses. You must not download or open files from sources that you do not trust, visit Web sites that you do not trust, or open e-mail attachments when your antivirus program is disabled. For additional information about computer viruses, click the following article number to view the article in the Microsoft Knowledge Base:

1. Stop all services that belong to the software package.
2. Set the Startup type to "Disabled." To do this, follow these steps:
   1. Click Start, click Control Panel, double-click Administrative Tools, and then double-click Services.
   2. In the Details pane, right-click the service that you want to configure, and then click Properties.
   3. On the General tab, click Disabled in the Startup type box.
3. Set the Start registry key of the corresponding filter drivers to 0x4. A value of 0x4 will disable the filter driver.To do this, follow these steps.
   
   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
   1. Start Registry Editor.
   2. Create a backup of the HKEY_LOCAL_MACHINE\System registry hive.
   3. Locate, and then click the following registry subkey:
      HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
   4. Click the entry for the filter driver that you want to disable.
   5. Double-click the Start registry setting, and then set it to a value of 0x4.
      
      Note This registry entry typically has a value of 0x3.
4. Restart the computer.

Most antivirus software uses filter drivers that work together with a service to scan for viruses. These filter drivers are still loaded after the service is deactivated. These filter drivers scan files as they are opened and closed on a hard disk. For troubleshooting purposes, temporarily remove the antivirus software or contact the manufacturer of the software to determine whether a newer version is available.

For additional information about how to disable antivirus software, click the following article number to view the article in the Microsoft Knowledge Base:

Example of filter drivers

This section describes some of the typical filter driver names by product:

Antivirus

• Inoculan: INO_FLPY and INO_FLTR
• Norton: SYMEVENT, NAVAP, NAVEN, and NAVEX
• McAfee (NAI): NaiFiltr and NaiFsRec
• Trend Micro: Tmfilter.sys and Vsapint.sys

Backup agent

• Backup Agent for Open Files: Ofant.sys
• Open Transaction Manager from Veritas BackupExec: Otman.sys (Otman4.sys or Otman5.sys)
  
  Note Use caution if you disable these filter drivers by using the method that is described in this article. If you do this, you may receive a "stop 0x7b" error message.
  
  The "stop 0x7b Inaccessible_Boot_Device" error message may occur if the following registry keys exist and contain references to the Otman5 driver when the Otman5.sys driver either does not exist on the hard disk or if the driver is set to disabled.
  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E967-E325 -11CE-BFC1-08002BE10318}\UpperFilters
  
  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{71A27CDD-812A -11D0-BEC7-08002BE2092F}\UpperFilters
  
  If you experience the "stop 0x7b" error message you should back up these registry keys and delete the Otman5 reference.

Driver registry settings

The following table lists valid settings and their description for the driver's Start and Type registry settings:

For additional information, click the following article number to view the article in the Microsoft Knowledge Base: The third-party products that are discussed in this article are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.