After you install a universal serial bus (USB) telephony device on a Windows Vista-based computer, this device is unexpectedly set as the default audio device. The USB telephony device can be a USB telephone, a USB handset, or a USB headset. This behavior occurs even though other audio devices are already installed on the computer.

In this situation, the computer cannot correctly play media or record media.

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This problem occurs because the system does not check the device type of the newly installed audio device. Instead, the system sets the newly installed device as the default audio device even though the device is a telephony device.

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Update information

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

Windows Vista, 32-bit versions

Download the 936004 package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=9B71C47E-149C-43F9-B641-61126CE82EE4)

Windows Vista, 64-bit versions

Download the 936004 package now. (http://www.microsoft.com/downloads/details.aspx?FamilyId=2A17B0E2-82A0-4C24-8055-EE9591DEBF3E)

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.

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Prerequisites

No prerequisites are required.

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Restart requirement

You must restart the computer after you apply this update.

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Update replacement information

This update does not replace any other updates.

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File information

The English version of this update 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 Vista, 32-bit versions

File name	File version	File size	Date	Time	Platform
Update.mum	Not Applicable	1,787	19-Apr-2007	20:07	Not Applicable
X86_1c84239218309afec9ac7d93795fd780_31bf3856ad364e35_6.0.6000.20581_none_f9e95f710cf6b0b3.manifest	Not Applicable	703	19-Apr-2007	20:07	Not Applicable
X86_microsoft-windows-audio-audiocore_31bf3856ad364e35_6.0.6000.20581_none_74ed9f6a00d6cd44.manifest	Not Applicable	139,515	19-Apr-2007	20:20	Not Applicable
Audiocore.mof	Not Applicable	4,349	07-Jan-2007	05:26	Not Applicable
Audiodg.exe	6.0.6000.20581	88,064	19-Apr-2007	01:35	x86
Audioeng.dll	6.0.6000.20581	398,848	19-Apr-2007	02:12	x86
Audiokse.dll	6.0.6000.20581	273,408	19-Apr-2007	02:12	x86
Audioses.dll	6.0.6000.20581	115,712	19-Apr-2007	02:12	x86
Audiosrv.dll	6.0.6000.20581	310,272	19-Apr-2007	02:12	x86
Encdump.dll	5.0.1.1	169,984	19-Apr-2007	02:13	x86

Windows Vista, 64-bit versions

File name	File version	File size	Date	Time	Platform
Amd64_c178c4416c36c8e38ba9bb7f5a319610_31bf3856ad364e35_6.0.6000.20581_none_3f6b32385bdc9bdc.manifest	Not Applicable	707	19-Apr-2007	20:07	Not Applicable
Amd64_microsoft-windows-audio-audiocore_31bf3856ad364e35_6.0.6000.20581_none_d10c3aedb9343e7a.manifest	Not Applicable	139,557	19-Apr-2007	20:24	Not Applicable
Update.mum	Not Applicable	1,797	19-Apr-2007	20:07	Not Applicable
Audiocore.mof	Not Applicable	4,349	07-Jan-2007	05:26	Not Applicable
Audiodg.exe	6.0.6000.20581	111,104	19-Apr-2007	02:01	x64
Audioeng.dll	6.0.6000.20581	480,768	19-Apr-2007	03:21	x64
Audiokse.dll	6.0.6000.20581	311,296	19-Apr-2007	03:21	x64
Audioses.dll	6.0.6000.20581	193,024	19-Apr-2007	03:21	x64
Audiosrv.dll	6.0.6000.20581	445,440	19-Apr-2007	03:21	x64
Encdump.dll	5.0.1.1	200,704	19-Apr-2007	03:21	x64

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To work around this problem, reset the device of your choice as the default audio device. To do this, follow these steps:

1.	Click Start, and then click Control Panel.
2.	In Control Panel, double-click Sound.
3.	On the Playback tab, click the audio device that you want in the Select a playback device below to modify its settings list, and then click Set Default.
4.	On the Recording tab, click the audio device that you want in the Select a playback device below to modify its settings list, and then click Set Default.
5.	Click OK.

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

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For more information about the same problem in Windows XP, click the following article number to view the article in the Microsoft Knowledge Base: For more information about how to determine an audio device type, visit the following Microsoft Web site: For more information, click the following article number to view the article in the Microsoft Knowledge Base:

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