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Consider the following scenario:

  • You register BizTalk Assembly Viewer (Btsasmext.dll) that is included in Microsoft BizTalk Server 2009.

  • You open Windows Explorer and leave a drive expanded. For example, you open your Drive C in Windows Explorer.

  • You start Microsoft Office Word 2007 or Microsoft Word 2010, and then you perform one of the following actions:

    • Click Open in the Open dialog box.

    • Click Save or Save As in the Save As dialog box.

In this scenario, Word stops responding. To recover from this issue, you have to exit Word by using Task Manager.


This issue occurs because of an error in BizTalk Assembly Viewer.


Cumulative update information

For BizTalk Server 2009, the hotfix that resolves this issue is included in Cumulative Update 1 for BizTalk Server 2009. 

For more information about how to obtain the cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base: 

2429050Cumulative update package 1 for BizTalk Server 2009

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 Web site: 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 the hotfix, you must have BizTalk Server 2009 installed.

Restart requirement

You have to restart the computer if the BizTalk Assembly Viewer is already registered when you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

File name

File version

File size
















Post-installation instructions

After you install this hotfix, register BizTalk Assembly Viewer again. To do this, open an elevated Command Prompt window, and then run the following command:

regsvr32 BTSAsmExt.dll


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


For more information about how to view assemblies by using BizTalk Assembly Viewer, visit the following Microsoft Developer Network (MSDN) website:

General information about how to view assemblies by using BizTalk Assembly ViewerFor more information about BizTalk Server hotfixes, click the following article number to view the article in the Microsoft Knowledge Base:

2003907 Information on BizTalk Server hotfixes

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