My Dell laptop has "MAXXAUDIO PRO", which does a bunch of heavy-handed stuff to make audio sound "better." I finally found the program when I was trying to figure out why my audio levels seemed to change.. My music would get louder over time, and if I moved the volume one increment up or down, it would drop back to the normal level. Turning off the sound-mangler solved that issue and allowed my music to sound the way it's supposed to.
It really frustrates me when manufacturers include crap like that.