I think this is either a driver problem or a 'settings' problem. Again, Vista x64 is kinda to blame. Try changing your audio settings to a lower quality in the control panel. I dont have the same problems as you but I do have another unrelated game will bring up errors if the audio quality is too high; bump it down a setting, and the world is fine.

All I can recomend is to play with the quality settings, as I defintely think this is more of a simple 'change some quality settings' problem.