here is what altec Lansing Support said:
Thank You for contacting Altec Lansing. The problem you are experiencing is most likely due to the fact that you are listening to the speakers in 6 channel mode. Please change to the 2\4 channel mode on the back of the subwoofer. 6 channel is only for audio encoded in 6 channel stereo not 5.1 surround sound. Most media is not available in that format such as DVD's and the like yet but, your system can handle it it's just that CD's and most DVD's don't have that encoding. Also, be sure to adjust your speaker settings in control panel to "Stereo surround speakers" and you should be all set. Again, thank you for choosing Altec Lansing and have a nice day..
Does it make sense?
What exactly is 6 channel stereo?
why are the knobs on my front speaker for center and surround dont effect anything?