It could possibly be a CSS issue but my best guess its its caused by invalid markup. When I check that url against the w3c validator, it shows a lot of errors, some of which can probably be ignored but I would fix the ones about missing or incorrectly formated closing tags. Some browsers are more graceful than others in dealing with missing closing tags and it seems in this case the most likely problem. Its either an image with a closing > that should be /> or a missing /> somewhere.
btw, noticed the meta tags for fixing the IE page flash problem when viewing the source of the page, nice trick, had not seen that.
Hope it helps,