iChat cannot connect with anyone on video chat or screen share.

[marcopchen]

I got a new Mac Mini with Snow Leopard around December and have been using iChat for awhile with no problems. About 2 months ago, my iChat stopped working. I can still instant message people, but I can't screen share or video chat with anybody. When I try it, it just says "Starting video chat" or "Starting screen share" for a very long time. Sometimes, after awhile, it will say something like "Could not start whatever because: Did not receive a response from whoever." My friends can video chat with other people, but I can't do it with them. I have tried it while talking to them on the phone, and they are accepting the invite. It also doesn't work when I am invited. I looked at the forums and haven't found a solution that pertains to Snow Leopard. I haven't changed my router or anything like that.