long time ago i read something about a sound bug in the Lighthouse Forum
maybe you need to update your sound-drivers or
eventually you need to switch off sound hardware acceleration
This is how to do (translated by google
)
Typing Start-> Run-> dxdiag
On the Sound tab, the current sound settings are displayed, and you can test DirectSound.
The slider for setting the sound hardware acceleration is used to correct audio glitches that might be caused by some audio drivers. The best way to troubleshoot DirectSound audio problems is to reduce the acceleration by one notch and re-testing the application. Lowering the Hardware Sound Acceleration Level from the default "full acceleration" may lead to non-functioning of advanced audio processing techniques such as 3D spatialization.