>Well, yeah, that is what I thought ... AFAIK, I haven't encountered this problem before (with something just flat out not working), but I have encountered the little security message in the yellow bar at the top of the browser before. This did not happen for your "Message view setup" javascript ... nothing at all happens.
I have changed your message window width from 640 to 850 until I find what is causing this. Let me know if that is ok for now.