When I started creating my forum not that long ago (www.thatgameforum.com), I checked it in Explorer and everything was fine.
Few weeks ago something weird happened though. I cannot say I did anything different, and I haven't been changing anything in the styles or templates.
This is how it looks like 'normally' in Firefox (where it looks like it should):
This is how it suddenly looks like in Explorer:
There seems to be a 'header' which there isn't (it's transparent) - I went in to have a look and nothing seems 'abnormal'. I can understand if there are browser differences but it use to work in both browsers ...