This clearly looks like a 'too big to fit' problem. While you fixed the dreaded IE box model bug with the correct doctype, something still prevails. In standards-compliant browsers, your menu will be as wide as you specify it (I think it is 120px) and it will stay that way regardless of what you do. If you have elements inside that are wider than that, they will simply hang over. In IE however, the menu will expand to accomodate larger elements. Meaning, if you have anything inside that takes up more than 120px the menu will expand without telling you. Once it is wider than 120px, it cannot be floated next to the main part and is pushed downwards. I don't have the resources to jab into your CSS right now and see what is causing your menu to grow in IE, but try to strip it down to bare bones to discover the problem.