Trust me this has me stumped(i work at a high school and i've seen everything from those extensions that make every 15 letters type a wrong letter to a pice of ham stuck in a cd drive....must have been hungary lol), its running mac os x, 256 megs ram....I've looked at all the standard options(this sound isnt even in the system sounds) And I don't think its application specific tho its done it 3 times when using msn messenger, but the sound is not in messenger either.........So no one else has had this problem? hmmmm