Hi
Thank you for using Microsoft Windows Vista Forums.
Method 1:
I would recommend updating the sound driver from the manufacturer’s website which will help you in resolving the issue.
Click on the link below for information on updating the driver.
http://windowshelp.microsoft.com/Windows/en-US/Help/b3c6477e-1111-4b9f-a52a-fffdc51e9c901033.mspx
Check if the issue is resolved.
Method 2:
Try running a program from Microsoft that automatically diagnoses and repairs problems with sound and audio on your computer. To do so, click this link and follow the instructions:
http://windowshelp.microsoft.com/Windows/en-US/Help/1e87a3e8-c0e8-49af-980f-9eb6686f42d21033.mspx
Check if the issue is resolved.
Please post back and let us know if this has helped to resolve your issue.
Regards,
KarthiK TP