Unfortunately I don't have an older version of IE to look at the page with, so it is hard for me to debug. It still has to be something with the html.
I see you have some tags above the <head> that should be inside of it. I doubt that is the issue.
I'd probably start removing other elements and playing on a test page to figure out the cause of the problem, and then go back to your working page and try to fix it. It has something to do with your css or html layout and probably only happens on certain versions of IE.
This is something I could help with in a premier support ticket.