OK, I have I weird problem, and I feel really stupid that I can't figure it out!! I've just been trying out a few free game downloads on my Macbook. The last one I tried was "Burning Monkey Solitaire". I decided I didn't like any of the games, so I got rid of them using Appzapper. I had my sound turned off at the time. I switched it back on to find background music playing even though I had no applications running. The music eventually faded out, leaving a constant background noise of gurgling water!! I rebooted the computer, only to find that the gurgling sound is still there! Even if I fire up iTunes and play a song, the gurgling sound is still in the background. You can't believe how stupid I'm feeling at the moment. I guess one of the games somehow left these sound effects behind. How do I stop it?????