Turning off Audio hardware Acceleration has fixed audio problems for me in the past. Here's how to do it in Win 7, 1: Right-click the speaker icon in your Windows system tray and select "Playback Devices." This menu option opens sound cards and speakers on your computer. 2: Click the sound card you want to set up. At the bottom of the sound card list, click the "Properties" button to open the main sound card information. 3: Remove the check mark next to "Acceleration" to disable the feature. Click "OK" to save the settings. Reboot the computer for the settings to take effect. Of course it's reversible. Before you try that, check your PC mixer for any sources that you can mute, as these can sometimes make a noise, especially if they're turned up high. As you're using USB, that'll be Line In 1, Line In 2, Mic etc.