IE Problem With Hover And Margin Bottom

I am sure it is a common problem

[Aberdeen]

When I run the mouse over an link, the link above moves up 2px. I am sure there is a simple explanation for this. Here is the code:

#left-nav a {
display: block;
width: 180px;
border: solid 1px #808080;
padding-left: 5px;
line-height: 16pt;
background: #F8F8F8;
text-decoration: none;
margin-bottom: 2px;
voice-family: "\"}\"";
voice-family:inherit;
width: 173px;
}
html>body #left-nav a {
width: 173px;
}
#left-nav a:hover {
background: #DEDEDE;
}

<div id="left-nav">
<a href="">A</a>
<a href="">B</a>
<a href="">C</a>
</div>

Hope someone can help.

Cheers

[DrDoc]

Sounds to me like there are some other styles conflicting with the rendering.