when I start up my computer, I have the mixer knob all the way on Playback. when I try to move the knob over to inputs, playback stops working altogether. if I try to go to something like youtube and try to start a video, it won't start at all. this goes the same for any type of audio file that I want to play on my computer. they just won't start. I have to restart my computer to get playback to work again. how do I make it so that I can switch from inputs to playback without any trouble? I have already looked in the users manual that came with it, and it didn't say anything about this problem.