Problems getting Submenus to display in IE 6

Question

I can't get my submenus to display for my website in Internet Explorer 6 or IE 7 (other than the home page, which strangely displays just fine)  It displays fine in Firefox, though. I am a novice and don't know much about this kind of stuff.

Can anyone please help? :)

Here is my test site URL:

www.lamp-light.com/greg2.php

And here is the CSS code that I am using:

@charset "utf-8";
/* CSS Document */

body{
padding: 25px;
font: .85em verdana;
color: #ffffff;
background: #000000;
background-image: url(http://www.lamp-light.com/lighthouse_picture.jpg);
background-repeat: no-repeat;
background-attachment:fixed;
background-position: top right
}

.content{
        margin-top:40px;
        width:800px;
        height:400px;
        overflow: auto;
        }

/*^'^ Navigation Structure ^'^*/
.nav-container-outer{
width:     100%;
width 2500px;   
background: #000000;
padding: 0px;
height: 74px;
/*background: url(images/nav-bg.jpg);*/
}
.float-left{
float: left;
}
.float-right{
float: right;
}
.nav-container .divider{
display:block;
font-size:1px;
border-width:0px;
border-style:solid;
}
.nav-container .divider-vert{
float:left;
width:0px;
display: none;
}
.nav-container .item-secondary-title{
display:block;
cursor:default;
white-space:nowrap;
}
.clear{
font-size:1px;
height:0px;
width:0px;
clear:left;
line-height:0px;
display:block;
float:none;
}
.nav-container{
position:relative;
zoom:1;
margin: 0 auto;
}
.nav-container a, .nav-container li{
float:left;
display:block;
white-space:nowrap;
}
.nav-container div a, .nav-container ul a, .nav-container ul li{
float:none;
}
.nav-container ul{
left:-10000px;
position:absolute;
}
.nav-container, .nav-container ul{
list-style:none;
padding:0px;
margin:0px;
}
.nav-container li a{
float:none
}
.nav-container li{
position:relative;
}
.nav-container ul{
z-index:10;
}
.nav-container ul ul{
z-index:20;
}
.nav-container ul ul ul{
z-index:30;
}
.nav-container ul ul ul ul{
z-index:40;
}
.nav-container ul ul ul ul ul{
z-index:50;
}
li:hover>ul{
left:auto;
}
#nav-container ul {
top:100%;
}
#nav-container ul li:hover>ul{
top:0px;
left:100%;
}

/*^'^ Primary Items ^'^*/   
#nav-container a{   
padding:7px 17px 7px 18px;
margin: 10px 0px 0px 0px;
color: #FFFFFF;
font-family: Trebuchet MS, Arial, sans-serif, Helvetica;
font-size:14px;
text-decoration:none;
font-weight: bold;
/*background: url(images/item-primary-bg.gif);*/
background-repeat: no-repeat;
background-position: top;
}

#nav-container a:hover{
color: #6C3600;
background: url(images/item-primary-bg.gif);
background-repeat: no-repeat;
background-position: center;
}

/*^'^ Secondary Items Container ^'^*/   
#nav-container div, #nav-container ul{   
padding:10px 4px 10px 4px;
margin:0px 0px 0px 0px;
background: url(images/item-secondary-container-bg.jpg);
background-repeat: repeat-x;
background-color: #FF9900;
border-bottom: 1px solid #CA6500;
}

/*^'^ Secondary Items ^'^*/   
#nav-container div a, #nav-container ul a{   
padding:3px 10px 3px 6px;
background-color: #FFFFFF;
background: url(images/item-secondary-bg.jpg);
background-repeat: no-repeat;
background-position: 0px 22px;
font-size:11px;
border-width:0px;
border-style:none;
margin: 0px 0px 0px 0px;
width: 149px;
}


/*^'^ Secondary Items Hover State ^'^*/   
#nav-container div a:hover, #nav-container ul a:hover{   
background-color: #FFFFFF;
background: url(images/item-secondary-bg.jpg);
background-repeat: no-repeat;
color:#0000CD;
}

/*^'^ Secondary Item Titles ^'^*/   
#nav-container .item-secondary-title{   
cursor:default;
padding:4px 0px 3px 7px;
color: #0000CD;
font-family: Arial, Trebuchet MS, Arial, sans-serif, Helvetica;
font-size:11px;
background: url(images/item-secondary-title-bg.jpg);
background-repeat: no-repeat;
font-weight:bold;
}

/*^'^ Horizontal Dividers ^'^*/   
#nav-container .divider-horiz{   
border-top-width:1px;
margin:5px 5px;
border-color: #C16100;
}

/*^'^ Vertical Dividers ^'^*/   
#nav-container .divider-vert{   
border-left-width:1px;
height:15px;
margin:4px 2px 0px 2px;
border-color:#AAAAAA;
}

Thanks!