Q:

Why does music start playing when I log in? 

When I login I suddenly start to hear music.  I haven't configured anything to do this.  As I start to do things the music stops.  What causes this? 

A:

When you login your cursor is positioned at the center of your desktop. 
If there happens to be an sound file there your system can helpfully preview (play) it. 
It may sound trivial or silly but when it happened it astonished me until I realized the reason.  It also surprised one other person I've corresponded with.