A hotfix rollup for the USB audio driver is available for Windows Vista-based and Windows Server 2008-based computers

This article describes a hotfix rollup for the USB audio driver, Usbaudio.sys, for Windows Vista-based and Windows Server 2008-based computers. This hotfix rollup fixes several problems and provides some improvements for the USB audio driver.

This hotfix rollup fixes the following problems:

• Some legacy USB MIDI devices do not appear in Windows Vista or in Windows Server 2008. These USB MIDI devices correctly appear in Windows XP.
• Some USB Audio devices display incorrect device names.
• In a USB Audio device, you cannot select the output source of a multiplexer (MUX) processing unit.
• A USB Audio device does not log to the same location as the Audio engine does.
• Surprise removal of a USB Audio device causes an application to stop responding or to use 100% of the CPU.
• The USB Audio driver incorrectly maps the center frequency to an incorrect value.
• The USB Audio driver cannot set a specific mode for a processing unit node.

This hotfix rollup includes the following improvements:

• The USB Bus drive can store a device startup failure.
• The USB device can save and restore the MIDI Processing Unit (MPU) state.
• The USB Audio driver can lock the AVStream queue on entry to standby or on exit from standby.
• The process for determining whether a USB Audio device is a communications device has been refined.

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: Note 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.

Important Windows Vista and Windows Server 2008 hotfixes are included in the same packages. However, only one of these products may be listed on the �Hotfix Request� page. To request the hotfix package that applies to both Windows Vista and Windows Server 2008, just select the product that is listed on the page.

Prerequisites

To apply this hotfix, the computer must run one of the following operating systems:

• Windows Vista
• Windows Vista SP1
• Windows Server 2008

Restart requirement

You have to restart the 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 Vista and Windows Server 2008 file information notes

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

  Version	Product	Milestone	Service branch
  6.0.6000.20xxx	Windows	RTM	LDR
  6.0.6001.22xxx	Windows Vista SP1 and Windows Server 2008 SP1	SP1	LDR

• Service Pack 1 is integrated into Windows Server 2008. Therefore, RTM milestone files apply only to Windows Vista. RTM milestone files have a 6.0.0000.xxxxxx version number.
• The MANIFEST files (.manifest) and MUM files (.mum) installed for each environment are listed separately . MUM and MANIFEST files, and the associated security catalog (.cat) files, are critical to maintaining the state of the updated component. The security catalog files (attributes not listed) are signed with a Microsoft digital signature.

For all supported 32-it versions of Windows Server 2008 and of Windows Vista

For all supported 64-bit versions of Windows Server 2008 and of Windows Vista

For all supported Itanium-based versions of Windows Server 2008 and of Windows Vista

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

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Additional file information for Windows Server 2008 and for Windows Vista

Additional files for all supported 32-bit versions of Windows Server 2008 and of Windows Vista

Additional files for all supported 64-bit versions of Windows Server 2008 and of Windows Vista

Additional files for all supported Itanium-based versions of Windows Server 2008