did you just update the driver? are you using the graphic equalizer? did you just roll back the driver? is it a new mp3? is it new to be played since driver fiddling (rather if you fiddled w\ driver have you played it since you did so?)
had the same thing happen, windoze update changed my digital graphics card to an analog driver (was in a hurry to get it done so I n00b'd) had a very similar problem, fucked up my sleep for weeks
Yeah, sometimes I'm convinced that windows makes up problems cause it likes hearing the error ping. Better then back in the day when I was playing with linux. Everything was working fine 'til LILO said no one day.