I have a set of Logitech speakers that are 5.1 surround sound. My computers specs are here: My Pc (It's stock) and under Sound it says I have 7.1 surround sound HD ready. But, on my 5.1 surround sound the only speaker not working is my Center one.. I don't know what is wrong with it, but it doesn't work... Please help. I have everything hooked up correctly.