Hey guys I just got my iMac like 4 days ago or so, and this is happening to me only sometimes. My problem is, when I open iMovie HD, and I click the little thing so that it turns on my iSight (you know the little camera icon, with the drop down list?) and when I click "Built in iSight" or whatever it says, I sometimes get this pretty loud noise, which sounds almost like feedback or something. I'm not sure what it is, but after that noise I go about normally and record video clips. And yea, this only happens sometimes. I don't know what this is. Anybody?