This might be 1 of 2 causes....
You may want to check the time compression settings within SH3Cmdr. Not entirely sure about the exact entry ( stuck at work at the moment
) but i think it was crew animation or something close to that. The original value should be 4. This could've caused your problem.
Otherwise you might wan't to look at the hardware accelaration for your soundcard. Turning that one down could perhaps also solve this problem.