I just got a MBP 13" (loving it of course). But every few minutes, like maybe 10-15 minutes (it doesn't seem like it's at regular intervals), a quick whooshing sound is made. I know that if I get new emails, or IMs, there'll be a little noise, and the icons in the dock will jump up and down, but that's not it. And it's not a mechanical noise - it's a system sound. Any idea what this could be? I guess it's not that big of a deal, but I'd like to know what the computer is alerting me about. Thanks!