Looks like hasLayout on #cmp-footer - try adding height:1% to the css for this element. Works with the dev toolbar.
EDIT: Hmm, maybe not, that element already hasLayout.
EDIT AGAIN: Your conditional comments don't look right. Try changing:
Code:
<!--[if eq IE 6]><link rel="stylesheet" media="all" type="text/css" href="styles/ie6.css" /><![endif]-->
<!--[if eq IE 7]><link rel="stylesheet" media="all" type="text/css" href="styles/ie7.css" /><![endif]-->
to
Code:
<!--[if IE 6]><link rel="stylesheet" media="all" type="text/css" href="styles/ie6.css" /><![endif]-->
<!--[if IE 7]><link rel="stylesheet" media="all" type="text/css" href="styles/ie7.css" /><![endif]-->