For diagnosis: disable all add-ons in Manage>Add-ons. If the sound and the messages stop then, it was one of those add-ons. Now find out which ones to enable again and which ones to delete.
Repost if it doesn't help.
Everytime I open Internet Explorer I can hear people talking like there is a backgroung website open and playing. How can i disable that?
Other problem, IE keep sending message ''Internet explorer has stop working''. What about that?