High CPU usage after you perform an operation in an application that uses common dialog boxes and browses a mapped drive in Windows 7 or Windows Server 2008 R2

Applies to: Windows Server 2008 R2 EnterpriseWindows Server 2008 R2 DatacenterWindows Server 2008 R2 for Itanium-Based Systems More


Consider the following scenario:
  • You have a computer that is running Windows 7 or Windows Server 2008 R2.
  • You map drives to an Active Directory integrated Distributed File System (DFS) root that has two root replicas on the computer. 
  • You perform an operation that triggers an application which uses common dialog boxes and browses the mapped drive. For example, you use the common dialog boxes in Word or Notepad to browse the mapped drive.  
In this scenario, the usage of one or more CPUs may reach 100 percent after several days of operation. 


This issue occurs because domain controllers return their targets in a different order for a referral. Additionally, the Partition Knowledge Table (PKT) cache becomes populated in a particular way which causes the target name resolution in the common dialog boxes to loop.

Note You can verify the cause of this issue by running the following command:

dfsutil cache referral

The result resembles the following:

Entry: \DFSSrv1\file
ShortEntry: \DFSSrv1\file
Expires in 0 seconds
UseCount: 1 Type:0x81 ( REFERRAL_SVC DFS )
   0:[\DFSSrv2\FILE] AccessStatus: 0 ( ACTIVE TARGETSET )

Entry: \DFSSrv2\file
ShortEntry: \DFSSrv2\file
Expires in 89 seconds
UseCount: 0 Type:0x81 ( REFERRAL_SVC DFS )
   0:[\DFSSrv1\FILE] AccessStatus: 0 ( ACTIVE TARGETSET )

Note "DFS Server1\file" and "DFS Server2\file" refers to each other.


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 the problem described in this article. 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 website: 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.


To apply this hotfix, you must be running Windows 7 Service Pack 1 (SP1) or Windows Server 2008 R2 SP1.

For more information about how to obtain a Windows 7 or Windows Server 2008 R2 service pack, click the following article number to view the article in the Microsoft Knowledge Base:

976932 Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R2

Registry information

To apply this hotfix, you do not have to make any changes to the registry.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.


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

More Information

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

824684 Description of the standard terminology that is used to describe Microsoft software updates