cant get my isight above 1fps


when i try to use my new isight with ichat, it will work well for the first 5 seconds or so, but then slow down to 1fps. i am using ethernet here in my dormroom, so i know its not a slow connection. this has happened with more than one chatting partner, so i know it doesnt have anything to do with the persom im chatting with. the funny thing is, i can see the other person clearly, as they will usually be running at 15 or 16 fps. what is wrong with my isight? i need it to start working.