I have hp pavilion mx70 computer and purchased lst year a Labtec 5.1 surround sound sysyem. It worked perfectly for 12 months but now only works on the FR and FL speakers plus sub woofer. When I go into sound manager it shows set up as headphones. ven when I reconfigure to a 5.1 system the other three speakers dont work. I have swapped speakers over to test that they all work. This confirms that the 5.1 system is fine and the problem lies with the computer. Any suggestions would be appreciated.