You receive an access violation error and the system may appear to become unresponsive when you try to install an update from Windows Update or from Microsoft Update

When you try to install an update from Windows Update or from Microsoft Update, you experience the following symptoms:

• The system may appear to become unresponsive when Windows Update scans for updates that use Windows Installer.
• You receive an access violation error in the Svchost.exe process. This process is related to the Automatic Updates service. This access violation occurs when you use Automatic Updates to scan for updates by using the daily automatic schedule or when you visit the Microsoft Update Web site to manually scan for updates.
• A memory leak occurs when Windows Update scans for updates that use Windows Installer.
• Windows Update scans take a very long time, sometimes hours, to finish.

To resolve this problem, follow these steps.

Step 1: Download and install update 927891

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

Download the Update for Windows XP (927891) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=7A81B0CD-A0B9-497E-8A89-404327772E5A)

Download the Update for Windows XP x64 Edition (927891) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=ECF96769-BEB6-4F7F-AC92-5BAEFB5632A3)

Download the Update for Windows Server 2003 (927891) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=2A4A8F01-ACD6-42A1-BB78-3D83CAEDA7A7)

Download the Update for Windows Server 2003 x64 Edition (927891) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=D63E8560-8F56-4EDA-A6E2-58C0B29B37CC)

Download the Update for Windows Server 2003 for Itanium-based Systems (927891) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=38FCE3F6-BCC4-4665-A66F-D9E1257C004F)

Download the Update for Microsoft Windows 2000 (927891) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=A6AD0BC9-1D4F-40CB-9A91-DCD6BC3AE6B2)

Release Date: June 26, 2007

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.

Step 2: Download and install Windows Update Agent (WUA) 3.0

To download WUA 3.0, click the link for the version of Windows that you are running.

x86-based versions of Windows

Download the WindowsUpdateAgent30-x86.exe package now. (http://go.microsoft.com/fwlink/?LinkID=91237)

x64-based versions of Windows

Download the WindowsUpdateAgent30-x64.exe package now. (http://go.microsoft.com/fwlink/?LinkID=91238)

Itanium-based versions of Windows

Download the WindowsUpdateAgent30-ia64.exe package now. (http://go.microsoft.com/fwlink/?LinkID=91239)

This problem was corrected in Windows Update Agent 3.0 and in update 927891.

More information for advanced users

Technical update: May 22, 2007

Microsoft has released a Microsoft Security Advisory on this problem for IT professionals. The security advisory contains additional security-related information about this problem. To view the security advisory, visit the following Microsoft Web site: Note This article discusses the MSI component fixes only. This fix is one component of a two-part fix that includes a Windows Update client software update. These updates will be deployed automatically by using Windows Update in May 2007 and June 2007. However, some customers may select to manually install these updates. To fully address the unresponsive system issue, both this fix for MSI must be installed and the Windows Update client must be updated to version 3.0. When you install the MSI fix and the new client, process-monitoring tools may still show CPU usage at near 100 percent. However, the system should still be responsive and should not lock up. If another task requires CPU cycles, they will be shared. However, if the system is idle, MSI will use the full cycles that are available to complete in the shortest time. If another task is running at the same time as MSI, the system may run slightly more slowly. However, the computer should still be responsive. Remember that you must install the MSI fix and the new client to address unresponsive or locked systems. It is expected that process-monitoring tools may still show CPU usage at near 100 percent, but computer unresponsiveness is expected. If you watch the process monitor, you may still see CPU usage at near 100 percent during some scans if the computer is otherwise idle. This is expected behavior.

Important Many instances of the Svchost.exe process may be running on a Windows-based computer. These Svchost.exe processes control certain tasks. The software update that is described in this article is only designed to address the problem that is mentioned in the "Symptoms" section. Other problems that you experience with Svchost.exe may require alternative resolutions or troubleshooting steps.

To resolve this problem, you must install this update together with the Windows Update Automatic Client 3.0. The Windows Update Automatic Client 3.0 will automatically be released through Automatic Updates by June 30, 2007. The updated Windows Client changes the thread modeling to move MSI scans to a thread that is separate from the user interface.

For the MSI update, install one of the following updates based on the version of Windows that is installed. To determine the version of Windows that is installed, follow these steps:

1. Click Start, click Run, type sysdm.cpl, and then click OK.
2. In the System Properties dialog box, click the General tab, and then notice the information that appears under System.

After you download the appropriate update, double-click the update package to install the update.

Note All versions of Windows XP, except for Windows XP Media Center versions, state "Version 2002" on the General tab in the System Properties dialog box. The update that is listed in the "Windows XP, all versions (including all versions of Windows XP Media Center)" section is correct for all versions of Windows XP. This includes all versions of Windows XP Media Center.

Note To install the update, you may have to apply the latest service pack for the version of Windows that you are running. For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:

Windows XP, all versions (including all versions of Windows XP Media Center)

Update information

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

Download the Update for Windows XP (927891) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=7A81B0CD-A0B9-497E-8A89-404327772E5A)

Download the Update for Windows XP x64 Edition (927891) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=ECF96769-BEB6-4F7F-AC92-5BAEFB5632A3)

Release Date: May 7, 2007

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

You must have Windows XP SP2 installed before you apply this update. You must also have Windows Installer 3.1 installed before you apply this update.

Restart requirement

You must restart your computer after you apply this update.

Update replacement information

This update replaces update the following update:

File information

Windows XP, 32-bit versionsWindows XP, 64-bit versions

Windows Server 2003

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

Download the Update for Windows Server 2003 (927891) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=2A4A8F01-ACD6-42A1-BB78-3D83CAEDA7A7)

Download the Update for Windows Server 2003 x64 Edition (927891) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=D63E8560-8F56-4EDA-A6E2-58C0B29B37CC)

Download the Update for Windows Server 2003 for Itanium-based Systems (927891) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=38FCE3F6-BCC4-4665-A66F-D9E1257C004F)

Release Date: May 7, 2007

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

You must have Windows Server 2003 SP1 or Windows Server 2003 SP2 installed before you apply this update.

Restart requirement

You must restart the computer after you apply this update.

Update replacement information

This update replaces the following update:

File information

Windows Server 2003, x86-based versionsWindows Server 2003, x64-based versionsWindows Server 2003, Itanium-based versions

Microsoft Windows 2000

Update information

Prerequisites

You must have Windows 2000 Service Pack 4 installed before you apply this update. You must also have Windows Installer 3.1 installed before you apply this update.

Restart requirement

You must restart the computer after you apply this update.

Update replacement information

This update replaces update 916089. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
The following files are available for download from the Microsoft Download Center:

Download the Update for Microsoft Windows 2000 (927891) package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=A6AD0BC9-1D4F-40CB-9A91-DCD6BC3AE6B2)

For more information about the terms that are used to describe software updates, click the following article number to view the article in the Microsoft Knowledge Base:

If you are still experiencing a problem that resembles the problem that this article describes, it may be a different problem. For more information about similar problems and resolutions, click the following article numbers to view the articles in the Microsoft Knowledge Base: If these Microsoft Knowledge Base articles do not help you resolve the problem, or if you experience symptoms that differ from those that this article describes, please search the Microsoft Knowledge Base for more information. To search the Microsoft Knowledge Base, visit the following Microsoft Web site: Then, type the text of the error message that you receive, or type a description of the problem in the Search Support (KB) field.