Video in iChat slows to 1 fps

Just recently, since yesterday, my girlfriend's video has slowed from 15 fps to 1 fps in about ten seconds. She hasn't updated any new software and her internet connection is fine, and the only thing that she has done is activate file sharing for a brief period and deactivate it again shortly thereafter. This started happening yesterday, and the night before everything was fine. I do not believe it is the camera's fault, as she has kept it safe and all connections are secure; it is also focusing properly and white-balancing. I believe iChat is for some reason degradating the framerate, or something along those lines. Can any one please help? I would appreciate it.