thats where those sounds are coming from. people are signing in and out…you don’t see the alert but you still hear the sound. My aim is set like that also…turn it on for a day or two and you’ll learn which people have which sounds…my computer burps and farts from time to time…it’s always someone i know signing in or out. nothing is wrong with your computer…or the software on it…aim just didn’t handle their shit right(as usual)