Website looks ok in IE7 but not other IEs - html

Question

This is how my website looks in Google Chrome and nearly all browsers except some versions of IE.
This is how it looks in IE8, IE9 and probably in IE6.
The funny thing is that the website looks ABSOLUTELY ok in IE7. I want you to help me solve the problem, but I don't really know which data to server you, but if you ask, I can provide everything you need.
Here's the header code:
<div id="header">
<div id="headercont">
<div id="headerlogo">
<img src="<?php echo dir;?>css/images/headerbg.png" class="header" />
</div>
<div id="menu">
<div id="mpointshighlight">
<div id="menupoints">
<?php echo menuSpace; ?>
<div id="menumain">Main</div>
<?php echo menuSpace; ?>
<div id="menuabout">About</div>
<?php echo menuSpace; ?>
<div id="menublog">Blog</div>
<?php echo menuSpace; ?>
<div id="menuphotos">Photos</div>
<?php echo menuSpace; ?>
<div id="menuvideos">Videos</div>
<?php echo menuSpace; ?>
<div id="menumusic">Music</div>
<?php echo menuSpace; ?>
<div id="menuprojects">Projects</div>
</div>
</div>
</div>
</div>
</div>
Here's the header CSS:
#header {
background-color:#00a2ff;
background-image:url('images/menubg.png');
background-repeat:repeat-x;
background-position:bottom;
width:100%;
min-width:1100px;
height:243px;
}
#headercont {
margin:auto;
width:1100px;
}
#headerlogo {
margin:auto;
width:1000px;
}
#menu {
width:100%;
height:44px;
}
#menupoints {
position:relative;
width:1000px;
font-size:24px;
font-family:verdana;
height:44px;
}
#mpointshighlight {
margin:auto;
width:1000px;
margin-bottom:10px;
background-repeat:no-repeat;
}
#menupoints a:link {
color:white;
text-decoration:none;
text-shadow: black 2px 2px 3px;
}
#menupoints a:visited {
color:white;
text-decoration:none;
text-shadow: gray 2px 2px 3px;
}
#menupoints a:hover {
color:white;
text-decoration:none;
text-shadow: black 2px 2px 3px, white 0 0 1em;
}
#menupoints a:active {
}
#menumain {
display:inline
}
#menuabout {
display:inline
}
#menublog {
display:inline
}
#menuphotos {
display:inline
}
#menuvideos {
display:inline
}
#menumusic {
display:inline
}
#menuprojects {
display:inline
}

Answer 1

Hard to be certain what the problem is without going into depth, but something that might help is to look into compatibility modes in IE:
http://msdn.microsoft.com/en-us/library/cc288325(v=vs.85).aspx
Specifically, tell IE8 and higher to emulate IE7:
Ensure this is the first HTML tag in the head.
As for IE6, depending on your target audience, you might be able to get away with ignoring it, otherwise it's a trawl through CSS I'm afraid!