Usually older sites will break on IE8, but there is a very simple solution that involves very little coding, even knowing that is not the best solution.
Add on your site homepage the following:
<meta http-equiv=”X-UA-Compatible” content=”IE=EmulateIE7? />
This will force the IE8 to emulate it’s atencessor, IE7 making the website works fully again.
This solution is the solution presented and used by WordPress.org developers at the moment.