Hi Bruce!
Welcome to Tom's Hardware,
Best way to tell what is activating a .wav file is to go to the Control panel, choose 'Sounds', then click the 'Sounds' tab at the top. The go down the list of the choices with speaker icons next to them, and you can 'test' the sounds, till you find the culpret. That will tell you what program, like, Windows, IE, or whatever, the sound is originating in. Then check out that program for the causal event.
Do you have Office running from Vista, after the upgrade? Possibly Office is letting you know you have a reminder or mail. There you would go to File / Options / Mail or Advanced to find the sound controls.