Microsoft KB Archive/942537

= An access violation may occur in the Telephony service that is run by Wvchost.exe when you run a Telephony API (TAPI)-related application on a Windows Server 2003-based computer =

Article ID: 942537

Article Last Modified on 10/11/2007

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APPLIES TO


 * Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
 * Microsoft Windows Server 2003, Datacenter Edition for Itanium-Based Systems
 * Microsoft Windows Server 2003, Datacenter x64 Edition
 * Microsoft Windows Server 2003, Enterprise Edition
 * Microsoft Windows Server 2003, Enterprise Edition for Itanium-based Systems
 * Microsoft Windows Server 2003, Enterprise x64 Edition
 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)
 * Microsoft Windows Server 2003, Standard x64 Edition
 * Microsoft Windows Server 2003, Web Edition

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SYMPTOMS
When you run a Telephony API (TAPI)-related application on a Windows Server 2003-based computer, an access violation may occur in the Telephony service that is run by Wvchost.exe. Additionally, the following event is logged in the System log: Event Type: Error

Event Source: Service Control Manager

Event Category: None

Event ID: 7034

Date:

Time:

User: N/A

Computer:

Description: The Telephony service terminated unexpectedly. It has done this 1 time(s).



CAUSE
This problem occurs because the telephony service does not return the correct status when this service processes requests to set the PassthroughMode property. Both Asynchronous Procedure Calls (APCs) to this service may share one data structure. After this service processes the first APC, the data structure is released. When this service tries to process the second APC, the data structure is detected as invalid. Therefore, this service stops responding.



Hotfix information
A supported hotfix is now 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 this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Windows Server 2003 service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or 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. To create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Prerequisites
To install the hotfix, you must have Windows Server 2003 with Service Pack 1 or Windows Server 2003 with Service Pack 2 installed.

Restart requirement
You have to restart your computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other previously released hotfixes.

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

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.

Windows Server 2003 with SP2, x64-based versions
For more information, 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



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.

Additional query words: TAPI unimdmat.dll AsyncProcessingHandler UmSetPassthroughMode

Keywords: kbfix kbqfe kbpubtypekc kbexpertiseadvanced kbhotfixserver KB942537

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