Drop Down menu

hi guys I have a problem,

I want to create drop down menu, below are the code:
<link href=“menu_style.css” type=“text/css”>
<div id=“menu”>
<ul>
<li><a href=“home.htm”>Home</a></li>
<li><a href="" class=“dissapear”>3D</a>
<ul class=“submenu”>
<li><a href=“3d_cg_animation.htm”>CG Animation</a></li>
<li><a href=“3d_stop_motion.htm”>Stop Motion</a></li>
<li><a href=“3d_illustration.htm”>Illustrations</a></li>
<li><a href=“3d_animated_films.htm”>Animated Films</a></li>
<li><a href=“3d_foam_sculpture.htm”>Foam Sculpture</a></li>
<li><a href=“3d_lenticular_printing.htm”>Lenticular Printing</a></li>
</ul>
</li>
<li><a href=“associates.htm”>Associates</a></li>
<li><a href=“client_list.htm”>Client List</a></li>
<li><a href=“testimonials.htm”>Testimonials</a></li>
<li><a href=“press.htm”>Press</a></li>
<li><a href=“contact.htm”>Contact</a></li>
<li><a href=“faq.htm”>FAQ</a></li>
<li><a href=“fun_stuff.htm”>Fun Stuff</a></li>
</ul>
</div>
and the css are:
#menu{
font-family:“century gothic”;
font-size:11pt;
color:#000;
text-decoration:none;
width:1024px;
position:relative;
padding:0;
margin:0;
z-index:10;
}
#menu ul li a, #menu ul li a:visited{
color:#000;
text-decoration:none;
display:block;
width:110px;
height:20px;
text-align:center;
line-height:20px;
overflow:hidden;

}
#menu ul li:hover ul.submenu a{
text-align:left;
margin:0;
width:115px;
height:20px;
padding:0;
}
#menu ul{
padding:0;
margin:0;
list-style-type:none;
}
#menu ul li{
float:left;
margin:0px;
padding:0px;
position:relative;
}
#menu ul li ul{
font-family:“century gothic”;
font-size:10pt;
display:none;
}

#menu ul li a:hover{
color:#fff;
}
#menu ul li:hover ul{
margin:0px;
padding:0 1px;
border-width:0 1px 1px 1px;
border-style:solid;
border-color:#999;
display:block;
position:absolute;

}
#menu ul li:hover ul li a:hover{
background-color:#999;
color:#fff;

}

when i test it in my MAC computer it’s worked but when i test it in PC the submenu doesn;t come out,

can anyone help me

thx