I often video chat between me and a relative who has a new 13" MBP. After chatting for a minute or 2, it will say (relative) canceled the chat. If I look over at the Jabber list their camera icon next to their name has disappeared. It usually comes back a few seconds later, and we can restart the chat. They aren't clicking on anything and it usually happens every minute or two, but sometimes we will be fine for a half hour. What is going on?