I have a problem playing AAC/M4A files using windows media player. It plays just like anything else does but with strong distortion, like volume turned up too loud. I tried turning down the volume both on the system and windows media player but it just gets quieter. I have a feeling this is codec-related?

Has anyone else had this problem? I am using Vista build 5456 at the moment, it's sound engine is different from XP and other versions of Windows. Maybe that has something to do with it..? Any ideas?