Menu items do not “open” when mouse hover over them?

Seems like the superfish menu plugin is not setting the CSS properties correctly when hovering over the menu item. You can fix this by updating the CSS in your styles.css file at line 155 from:

.nav2 li.sfHover ul, ul.nav2 li:hover ul {
    background: none repeat scroll 0 0 #B3B3B3;
    color: #FFFFFF;
    text-decoration: none;
    z-index: 1000;
}

to:

.nav2 li.sfHover ul, ul.nav2 li:hover ul {
    background: none repeat scroll 0 0 #B3B3B3;
    color: #FFFFFF;
    text-decoration: none;
    z-index: 1000;
    visibility: visible!important;
    display: block!important;
}

This overrides the visibility and display settings that are being set inline on the element itself by superfish.js, but are not being cleared when you hover over the menu item.