Background Color which spoils the design

hi

I’ve got a little problem with my menu : I assigned a background-color property with my a:hover. The link is inside a list. With Firefox it’s just perfect, but it’s not that good with IE : when the cursor is over the link, the menulist moves a few centimeters to the left ! Without the background-color property, it just stays quiet at its own place. Can you explain/solve this, cause I don’t understand ?

the site : [url]http://swingfiler.bleuarff-corp.info/test/index.php[/url] (it’s in french, but you don’t have to understand the text to see the problem :p )
the stylesheet : [url]http://swingfiler.bleuarff-corp.info/test/styles/design.css[/url]
And the concerned part:

[CODE]#leftmenu{
position : absolute;
left : 0%;
top : 0%;
width : 17%;
max-width : 17%;
padding : 0.5% 0% 1% 3%;
margin : 0em;
border : 1px solid red;
}

#leftmenu, .menuliste{
font-size : medium;
font-weight : bold;
}

.menuliste{
width : 90%;
margin : 0em;
padding : 0em;
list-style-image : none;
list-style-type : none;
/* padding-left : 0%;*/
border : 1px solid green;
}

.menuliste li{
display: inline;
}

.menuliste a{
color : black;
display: block;
text-decoration: none;
margin : 0em;
padding : 0em;
}

.menuliste a:visited{
color : black;
}
.menuliste a:hover{
background-color: orange;
text-decoration: none;
color : black;
margin : 0em;
padding : 0em;
}[/CODE]

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