Sound

[Mark]

I recently have been noticing an issue with my sound on a
gaming demo. I understand that these demo's can cause
file corruption. I had hissing sounds in this game and
later no sound at all. I bought a new sound card and
still to no resultion. I'm at a loss as everything is
showing working properly. My system is XP pro and SB live
audio. It is compatible in every way. Could it be my
motherboard is becoming fualty!? My device mgr is showing
fine in sound,audio, controllers and the driver is
updated. Only once when I shutdown did it make the
shutdwn sound and upon reboot, the intro sound is not
there as well as all sound. Help Please! email possible
solution.