try this, it may haelp
1. Exit iTunes
2. In Windows click on Start - Control Panel - QuickTime
3. For QuickTime 7, click on the Audio tab. Under Devices, click to select Safe mode (waveOut only) and click on Apply.
4. For earlier versions, click to select the Sound Out option, and under Choose a device for playback: click to select waveOut:Windows' preferred device or waveOut:name_of_soundcard
5.Reboot your PC