Recently I've noticed my Mac Pro playing the Basso sound effect every once in awhile, seemingly at random. It just happened a moment ago while I was Macrumors foruming, so I thought I'd see if anyone has some insight. Running right now in my dock is Activity Monitor, Dashboard, iTunes, Safari, Mail, Address Book, Preview, and Chronosync. Connect360 is up in my menubar (xbox isn't on, though) and Quicksilver is running in the background. I'm connected to the net through Airport, and I'm using a bluetooth Mighty Mouse and Apple keyboard. My iPod is plugged in and mounted on the desktop. My default alert sound is Pop. As far as I can figure out, I don't have anything running that should be giving me this Basso sound effect, and no window pops up or apps bounce in the Dock. The Basso sound doesn't happen too often, but I've noticed it probably 3 or 4 times this week. Anyone have any ideas?