After you resume a Windows Vista-based computer from sleep or from hibernation and then restart the computer, a high definition audio (HDA) device may no longer work. The device may be a sound device or a modem. You may see an "X" 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.
To resolve this problem, install update 929685. To install this update, visit the following Microsoft Web site:
Microsoft, Windows vista, Hibernation, Fix