it at least works for me, so i registered in this forum to share it on the net.
i have p6t asus motherboad and using windows 7, suddenly i found center and subwoofer are not working correct, so after 2-3 days of confusing i found this for solution:
turn of the pc and unplug all of the cables ( usb, graphic cards plugs, keyboard&mouse, power) and unplug the main power plug also, because even when the computer is turned off, motherboad may using power! i dont know too much but i heard this. and then after 2-3 hours, turn on the computer and all of speakers are working!
hope it helps. cheers