Hi ASTRA52,
I would suggest you to run the Hardware and Devices troubleshooter.
Open the Hardware and Devices troubleshooter by clicking the Start button , and then clicking Control Panel. In the search box, type troubleshooter, and then click Troubleshooting. Under Hardware and Sound, click Configure a device. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
http://windows.microsoft.com/en-us/windows7/Open-the-Hardware-and-Devices-troubleshooter
I would also suggest you to install the latest sound drivers compatible for Windows 7 from the manufacturer’s website.
http://windows.microsoft.com/en-US/windows7/Tips-for-fixing-common-sound-problems
You may also refer the below mentioned link.
http://support.microsoft.com/kb/316992
Hope this information helped!
Thanks and regards,
Fouzan – Microsoft support.
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