Child pages disabled in IE

I have a site set up with the Wordpress Twenty Ten theme. I edited the CSS in order to make the nav bar elements stretch across the nav, instead of piling up on the left side. Now, however, the top level pages can be clicked on, put the child pages are disabled and disappear upon scrolling over them in IE. Beyond bizarre. Any help would be much appreciated.

Here is the site: http://www.econforensics.com

Here is the code: http开发者_如何学C://pastebin.com/svx8hNeK

Thank you,

Alex

It's very simple to fix this problem in IE7:

In style.css, at approximately line 407, change this:

#access .menu-header li,
div.menu li {
    float: left;
    position: relative;

}

to this (there was already an empty line for me!):

#access .menu-header li,
div.menu li {
    float: left;
    position: relative;
    z-index: 1
}

It fixes the issue, which was caused by a bug in IE7.