Ever since I bought my Macbook Air about a month ago, it makes this random sound from time to time and it's really annoying. It started even before I downloaded any programs. It's kind of like a tri tone sound, but I can't record it, because it comes at random. I looked at other threads, but couldn't find the same sound. Can anybody please tell me how I can figure out which program is making the sound and how can I stop it? Thanks!