We had some issues with that specific sound card during test but we thought we had it licked.
Joe may be able to shed some light into this.
In either case make sure your have DirectX installed and that your sound card is listed as directx compliant. You can check this by running dxdiag and checking under sound.
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Sarge is coming...
Richard Arnesen
Director of Covert Ops
Shrapnel Games
http://www.shrapnelgames.com