It looks like there is a specific part of the js code that is doing this on your page. Open up the CSSMenuWriter > cssmw_home > menu.js. In this file look for the following code on line 42:
if (this.browser.isLteIE7) {
Update this line to be like this:
if (this.browser.isIE6) {
When I tried this it seemed to get the menu working correctly for me. Please give this a try to see if it fixes the problem you are experiencing.