"DRIVER_IRQL_NOT_LESS_OR_EQUAL (d1)" Stop error and an ISA Server 2006 crash may occur

Microsoft Internet Security and Acceleration (ISA) Server 2006 may crash because of Fweng.sys, and then you receive a Stop error message that resembles the following:

This issue occurs because of a code error in ISA Server 2006.

Hotfix rollup information

To resolve this issue, install the hotfix rollup package that is described in the following Microsoft Knowledge Base (KB) article

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: To apply this hotfix after you install this hotfix rollup package, modify the value of the�DisablePeriodicPortCleaning registry key. To do this, follow these steps:

1. Locate and then click the following registry key:
   
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Fweng\Parameters\DisablePeriodicPortCleaning
2. On the Edit menu, click Modify.
3. Type 1, and then press ENTER.

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

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base: