#menu {
width: 200px; /* set width of menu */
margin: 0px;
z-index: 100;
} 

#menu ul { /* remove bullets and list indents */
list-style: none;
padding: 0;

}

/* style, color and size links and headings to suit */
#menu a {
display: block;
border-bottom-style: dotted;
border-bottom: #ffffff;
border-bottom-width: 1px;
margin: 0px;
padding: 3px 3px 3px 20px;
color: #006634;
text-decoration: none;
background-image:url(../Media/Images/btn_background.jpg);
background-repeat:no-repeat;
}

#menu a:hover {
border-bottom: #006634;
}
#menu li {
/* make the list elements a containing block for the nested lists */
position: relative;

} 

#menu ul ul ul {
position: absolute;
top: 0;
left: 100%; /* to position them to the right of their containing block */
width: 100%;/* width is based on the containing block */
background-color:#B5E89E;
}
div#menu ul ul ul,
div#menu ul ul li:hover ul ul
{display: none;}

div#menu ul ul li:hover ul,
div#menu ul ul ul li:hover ul
{display: block;}
<!--[if IE]>
<style type="text/css" media="screen">
body {
behavior: url(csshover.htc); /* call hover behaviour file */
font-size: 100%; /* enable IE to resize em fonts */
} 
#menu ul li {
float: left; /* cure IE5.x "whitespace in lists" problem */
width: 100%;
}
#menu ul li a {
height: 1%; /* make links honour display: block; properly */
} 
</style>
<![endif]-->