As far as I know, this started happening with the new theme. I noticed that any post with the code tags in a smaller window will flow outside the right border. The window size that I used was 958x843, which I don't believe is that small. I don't have the problem if my window is maximized (my monitor has 1680x1050 native resolution). I've attached a screenshot of my browser (Firefox 3 Beta 5 in Hardy). The thread is here.