iChat AV/iSight very strange flickering problem

So my whole family receives iSights for Christmas this morning, "awesome!" i think, so I plug 2 in to different computers, everything works fine, go apple! Then I tried it again and I get this very strange flickering problem where on my screen, the video window keeps flickering between the video feed from my camera and the feed from the other camera, like it can't decide which is which. And the iSight makes a strange noise over and over. I tried switching iSights thinking it was the actual hardware, but same problem. Everything appears fine on the other computer, they can see both themselves and me perfectly. But mine just flickers between only me or only them (constantly). I even tried rebooting and then reinstalling iChat. No luck. Any ideas?