When I check my mail manually and I have no mail, I get a high-pitched\nshrieky alert sound. I have no idea where it came from, because the\nsound isn't even in my list of sounds (System Preferences/Sound). I can\nget rid of it by unchecking "play sounds for other mail actions" in Mail\npreferences, but I'd prefer not to. It seems like this sound started\nhappening after I installed Skype. But Skype doesn't have that sound in\nits sound choices either. Anyone have a clue?