IE Changes layout on Hover

IE changes the layout of my site frmo incorrect to correct when the :hover function of CSS is active. After that the site remains correct.
Is this a bug of MS, or is it a problem in my CSS?
the page is http://www.homeparties.no
This is the part of the CSS that seems to be the problem (showing the links in the blocks).

div#links {
	position: relative; 
	float: left; 
	/*width: 800px;*/ 
	width: 90%;
	height: 1000px;
	font: 16px Verdana, sans-serif;
    	border-width: 5px;
    	border-style: solid;
    	border-color: #DDDDDD;
	background: #468 url(./imgs/bg11.png) 0 0;
    	margin-left: 0.5%;
    	margin-right: -2%;
}
div#links a {
	display: block; 
	text-align: center; 
	font: bold 1em sans-serif;
   	padding: 5px 10px; 
	margin: 0 0 1px; 
	border-width: 0; 
   	text-decoration: none; 
	color: #FFC; 
	background: #DDD;
   	border: 5px solid #9accff;
   	position: relative;
   	float: left;}
div#links a:hover {color: #411; background: #9accff;
   border-color: #DDD;}

Code (markup):

 

Change this:

	/*width: 800px;*/ 
	width: 90%;

Code (markup):

to this:

	width: 800px; 
	/*width: 90%;*/

Code (markup):

Then fix the percentages in:

/*
div#linkplace
{
	margin-left: 40%; 
	margin-right: 40%;
	margin-top: 20%; 
	margin-bottom: 20%;
}*/

Code (markup):

I've commented that whole bit out for the moment, and the layout is fine when I do that.

I'd also recommend not linking 4 stylesheets to the page. That gets really confusing, really fast. Try consolidating them into one stylesheet or leave the ones that don't pertain to this page out (preferably the first). 4 stylesheets means you'll have to pay very close attention to precedence.