It looks like its this styling that is causing the issue:
ul li ul {
left:-800px; display:none; height:150px;
}
ul li:hover ul, ul li.sfhover ul {
left:743px; position:absolute; display:block; top:80px; height:150px;
}
ul li ul li:hover, ul li ul li.sfhover {
left:743px; display:block; top:80px;
}
ul li ul li:hover, ul li ul li.sfhover {
display:block; top:80px;
}
You'll have to modify that so the mouseover will perform the way you want it to.