We have discovered this problem on some computers that have multiple audio playback device. If you experience this problem, please try playing the game with only one audio device enabled.
to do this on Windows Vista/7, go to Control Panel -> Sound. Click the Playback tab, then right-click and Disable every device, other than the one you're actually using ("Realtek High Definition Audio" for instance).
Afterwards, if you wish to re-enable these devices, go back to this window, right-click an empty area and select "Show disabled devices". You should now be able to right-click the disables devices and un-check "Disabled".
To do this on Windows XP, go to Control Panel -> Device Manager, then expand the group "Sound, video and game controllers." Disable all devices [b]except for[/b]: - the sound card you're actually using ("Realtek High Definition Audio" for instance),
- any game controllers you may be using ("HID device", "Human Interface Device", etc.),
- the following: "Audio Codecs", "Legacy Audio Drivers", "Legacy Video Capture Devices", "Media Control Devices", "Video Codecs".
Basically, you'll be disabling devices such as S/PDIF and your graphics card's HDMI audio output (unless that's what you're using, of course).