FIX: The guest operating system may crash when you perform a live migration of Hyper-V virtual machines in a Windows Server 2008 R2 environment

To resolve this problem, install this update on the host computer where the Hyper-V virtual machines are located.

Update information

To resolve this problem, install this update from Microsoft Windows Update.

Additionally, you can install this update from the Microsoft Download Center.

The following files are available for download from the Microsoft Download Center:

Download the update package now.

Release Date: January 10, 2012

For more information about how to download Microsoft support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help prevent any unauthorized changes to the file.

Prerequisites

To apply this hotfix, you must be running Windows Server 2008 R2. 

Registry information

To use the hotfix in this package, you do not have to make any changes to the registry.

Restart information

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The English (United States) version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

Windows Server 2008 R2 file information notes

Important Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.

• The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
  
  

  Version	Product	Milestone	Service branch
  6.1.7600.16xxx	Windows 7 and Windows Server 2008 R2	RTM	GDR
  6.1.7600.20xxx	Windows 7 and Windows Server 2008 R2	RTM	LDR
  6.1.7601.17xxx	Windows 7 and Windows Server 2008 R2	SP1	GDR
  6.1.7601.21xxx	Windows 7 and Windows Server 2008 R2	SP1	LDR

  
  
• The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows 7 and for Windows Server 2008 R2" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.

For all supported versions of Windows Server 2008 R2