So the whole right side of the page is an addon? Because you can't click on anything. The New Posts, New Profile posts, or anyone's name like you normally could. Not just Shoutbox.
No, but an issue with an addon can affect more than the addon itself. Not that I'm saying that the chat's necessarily the culprit in this case. Could be a Chrome bug for all I know. I don't use Chrome so I don't have this problem.