This problem could be occuring, because by default IE8 is standards compliant. If the forum code is generating non-standard html, there could be issues. Try adding the forums to the pages to be viewed in Compatibility View. (Tool -> Compatibility View Settings) In order to do a quick test if this works, try clicking on the Compatibility View button, to the left of refresh and the right of the address bar (at least that is where it is on my browser).