IE Drop menu not working - php

Question

I have a website with a css drop menu, which works fine on chrome and firefox, but in IE the drop menu doesn't display.... it's almost like it doesn't exist at all...
I've tried multiple times to copy some code or menus from other sites i have that do work in IE, but without success.
Here's the html...
<ul id="menu">
<li>INTRO |</li>
<li>HOME |</li>
<li>ACCOMMODATION & RATES |</li>
<li>INFO |</li>
<li>ACTIVITIES |
<ul class="sub-menu">
<li>GARDEN ROUTE ACTIVITIES</li>
</ul>
</li>
<li>GOLF |</li>
<li>NEWS |</li>
<li>CONTACT US |</li>
<li>DIRECTIONS |</li>
<li>GALLERY</li>
</ul>
the CSS
/*Initialize*/
ul#menu, ul#menu ul.sub-menu {
padding:0px 0 0px 0;
margin: 0px;
/*background-color:#9A844C;*/
}
ul#menu li, ul#menu ul.sub-menu li {
list-style-type: none;
display: inline-block;
display:inline;
}
/*Link Appearance*/
ul#menu li a, ul#menu li ul.sub-menu li a {
text-decoration: none;
color: #573A2F;
padding: 0px;
display:inline-block;
font-size:10px;
}
ul#menu li a:hover {
text-decoration: none;
color: #000;
padding: 0px;
display:inline-block;
}
/*Make the parent of sub-menu relative*/
ul#menu li {
position: relative;
padding-bottom:5px;
z-index:100001;
}
/*sub menu*/
ul#menu li ul.sub-menu {
display:none;
position: absolute;
top: 20px;
left: 0;
width: 200px;
background-color:#E2D9C6;
z-index:100001;
}
ul#menu li:hover ul.sub-menu {
display:block;
z-index:100001;
}
ul#menu li ul.sub-menu:hover {
display:block;
color: #573A2F;
z-index:100001;
}
Any help would be greatly appreciated...

Answer 1

I have checked with your code and it is working in my system. I have checked in IE7,8 and 9.
Another suggestion just change below css and check again:
I have just changed from "ul#menu li ul.sub-menu:hover" to "ul#menu li:hover ul.sub-menu"
ul#menu li:hover ul.sub-menu {
display:block;
color: #573A2F;
z-index:100001;
}

Answer 2

As others have stated, your code works with IE7, IE8 and IE9.
If the issue is really with IE6, I am not going to solve your current problem, because of the following line:
It is not worth it
And with this i don't mean that YOUR WORK is not worth it, but that nobody should still develop for IE6. It's a 10 years old browser, which should be put to sleep as soon as possible. And it's not just my opinion, but Microsoft's! see HERE and notice the Microsoft copyright at page footer.
Also, see HERE for browser usage statistics: IE6 is used by just 0.6% of internet users. Is your time worth it?