A high definition audio (HDA) device may no longer work after you resume Windows Vista from sleep or from hibernation. The device may be a sound device or a modem. You may see an "X" character appear on the speaker icon in the notification area.

Because of this problem, you no longer hear any sound, or you cannot use the modem. This problem occurs even though you have installed the update that is described in Microsoft Knowledge Base article 929685. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Note An updated version of this article and hotfix is now available. To resolve this problem using the latest updates from Microsoft, see the following article in the Microsoft Knowledge Base: For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Service pack information

To resolve this problem, obtain the latest service pack for Windows Vista. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Update information

To resolve these problems, install the update that is described in Microsoft Knowledge Base article 937077.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Windows Vista Service Pack 1.

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

Troubleshooter: No audio in Windows (http://windows.microsoft.com/en-us/windows/help/no-sound-in-Windows)

Music and sound help with Windows 7 (http://windows.microsoft.com/en-us/windows7/help/music-sound)