For several weeks now my laptop has been coming up with a "ding" sound (sounds like hitting a bell at a hotel counter) at the oddest times. I have explored sounds and every program I can think of and can't figure out what is making it happen. No program in visible use at the time the ding happens is responsible. Today I was using a different laptop which is seldom used, and it happened there too. I have a few programs in common that I now of, but have checked their sounds with no results. Does anyone have any ideas?