in the menu.css file, edit the first rule:
ul#cssmw1 {
cursor: default;
list-style-type: none;
margin: 0 0 0 0;
padding: 0 0 0 0;
}
and add position:fixed; to it:
ul#cssmw1 {
cursor: default;
list-style-type: none;
margin: 0 0 0 0;
padding: 0 0 0 0;
position: fixed;
}