Battlefield 1942

When I play the demo for this game (will try the full version today) with directsound hardware acceleration as high as possible, my game play is choppy--meaning, everything second or so the game drops a frame. When I put the hardware acceleration slider to zero, the game acts normally for about 10 minutes until the sound of a machine gun is in an infinite loop, which can get very annoying...

any ideas?

Thanks,
CaP