The device driver might not be installed or it might not be installed properly. To determine whether Device Manager can find the device driver, and to install or reinstall the driver if necessary, follow the procedures below in the order they're given.
Follow these steps to determine whether Device Manager can find the device driver:
In the list, double-click the type of device, and then locate the specific device that isn't working properly.
If an exclamation mark appears next to the name of the device, Device Manager can't find the device driver. Go to "Use Windows Update to find a device driver."
If no exclamation mark appears next to the name of the device, go to "Uninstall and reinstall the device driver."
Close Device Manager.
Follow these steps to manually uninstall and reinstall the device driver:
In the list, double-click the type of device, and then locate the specific device that isn't working properly. Right-click the device, and then click Properties.
Click the Driver tab, click Uninstall, and then click OK.
In the Device Manager dialog box, click the Action menu, and then click Scan for hardware changes.
If you see a message saying that Windows has to install driver software for your unknown device, click Locate and install driver software (recommended).
If the device driver is installed and working properly, you have resolved the problem. If the device is installed but isn't working properly, go to "Use Windows Update to find a device driver."
To use Windows Update, you must be logged on to the computer as an administrator. Follow these steps to use Windows Update to find a device driver:
Click Check for updates.
To see if any updated drivers are available, click View available updates.
If updates are available, click the driver that you want to install, and then click Install.
If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
If Windows Update can't locate the required device driver, contact the device manufacturer to download the latest device driver for Windows Vista.
For more information about troubleshooting audio problems after you install a Windows Vista service pack, see Why can’t my computer play sound after installing a Windows Vista service pack?