So I am using Logitech Z-5500s with my MP. Under the sound settings with digital optical selected, it says: "The selected device has no output controls." And at the top of the screen where it shows the volume, it is grayed out. And when I hit the volume up/down/mute button on my keyboard, it has a circle with a line through it. If I play a song on iTunes, sound comes out and I can control the volume through the Logitech controller like normal. But even when something is playing, it still won't let me adjust the volume through the computer. Does anyone know what is going wrong?