I've now noticed that if I turn down the music volume slider to zero it's not just the music that stops playing. I can also no longer hear any other in-game audio such as my footsteps as I move, NPC voices, gunshots and even game menu interface clicks. The Radio music still plays fine with Music volume at zero though. If I turn the music volume levels up I can hear everything again.
Isn't it a bit dumb to tie non-music effects into the music volume level setting? What is the point of having Voice and Effects voume sliders if the Music slider controls everything?
I'm playing on Windows 7 64-bit, 2Gb Ram, SoundBlaster X-FI Xtreme Gamer. SounbBlaster drivers were updated an hour ago after encountering this problem in Fallout 3. Also note that all my other games (Dragon Age: Origins, World of Warcraft, StarCraft 2, Silent Hunter 5 and other games are not having issues seperating music levels from basic sound effects and NPC speech.