I can't seem to get the z-index to make any difference. You could add a left margin to your ( isi2010/CSSMenuWriter/cssmw2/menu.css ) 'ul#cssmw2 ul.level-2 > li > a {' rule:
ul#cssmw2 ul.level-2 > li > a {
background-image: url("../cssmw2_images/alpha80.png");
border-bottom: solid 1px #fff;
border-right: solid 1px #fff;
color: #173232;
display: block;
font-family: Arial, Helvetica, sans-serif;
font-size: 10px;
font-style: normal;
margin: 0 0 0 81px; // Changed from 0 0 0 0;
padding: 5px 5px 5px 5px;
text-decoration: none;
text-transform: uppercase;
width: 100px;
z-index:999;
}
Hopefully someone will advise re the z-index.