There's a driver conflict or a damage driver. Try to skip in the middle of each song and see if the sound comes back. I don't know if uninstall and reinstallation will fix your problem, but try anyway. I had the same issue and that I had to reinstall the Windows operating system twice. Sometimes these happen when you integrate a new service pack on your OS installation. I don't know why but it does. Maybe the integration requires other updates, who knows? Sometimes, it has something to do with the order of the installation; I've done so man of it and found something that works for me.