IE being stubborn with a drop up/down menu

I have a drop up/down menu located at http://islandicecream.sitesbyjoe.com (this is a site I'm building). I'm at the fun part where I test all the IE versions and get them working as best I can.

The particular trouble I'm having is getting IE to make the links in the drop down span 100% o开发者_StackOverflow社区f their parent container. I feel like I've tried everything and it still won't behave.

Any suggestions?

Found the problem. You need to specify a width for #nav ul.sub_nav. Since there is no width specified to that element, its children don't know what 100% means. Well at least that is the case in IE7.