My son tried to buy this game via your webiste using IE8 on XP, but as soon as he clicks the Buy Now link (and it really doesn't matter where on this site - all links lead to the same place), he gets the "Determine connection problems" screen. In IE9 on Vista or Chrome on XP there is no issue or whatsoever.

May be something you want to look into. I'm sure he's not the only one using IE8.