It sounds from talking with others that several people are having a similar problem:

If my connection drops (i.e. I'm using a wireless connection) for a second, my chat window closes and I can't get logged back onto Chat. When I try, it says that there's already a user logged in by my name and to use another login.

I've tried closing my browser and rebooting, but it seems I have some sort of a timeout (about 10 minutes) before I can log back in. People who are there still see me as in the chat, and then see a quick reconnect as I finally get logged back in (except I don't see any of what people are saying until I'm logged back in on my browser).

Did that make sense?