When I want to reply or create a new thread while using Firefox I get a very wide screen.
I attached a screenshot of how it looks like for me:
Sorry I didn't make it smaller, just wanted to show u how annoying it is when u have a horizontal scrollbar...
I had the same error on my forum. Solution is to put big smileys into "More" window and leave all standard small smileys on the front page...
-edit-
Just checked with Internet Explorer 7 again and the page is wide as well. My resolution is 1204x768...