I Just signed in on this page and it worked fine, but I found it happening in another scenario now too.
I had one window open on the homepage, and one window opened on a thread. After clicking on a recent thread (from the homepage) to open in a new window (basically opening a 3rd window), the homepage window loaded the same thread too.
It seems that having multiple browser windows open is causing some strange things to occur.
I'm running firefox btw.