IE7 Header problems

Hi
Have added a header with links to our site [url]www.yakoozo.com[/url], and all seems well across all browsers apart from IE7.
The links display vertically instead of horizontally for some reason and cannot fix it.

Any help would be great…

CSS code is as follows.

/* header bar starts */

.headertabs
{
background: url(“http://www.yakoozo.com/images/headerhome.png“) repeat-x top left;
height:19px;
padding-bottom:10px;
margin-top:-10px;
}

ul
{
list-style-type:none;
margin:0px;
padding:0px;
}

ul.dropdown { position:relative ; font-size:11px; font-family:Verdana, Arial, Geneva, sans-serif; width:800px; margin:10px; padding-top:5px; }
ul.dropdown a:hover { text-decoration: underline; }
ul.dropdown a:active { text-decoration: underline; }
ul.dropdown li a { float: left; display: inline-block; list-style:none;padding: 0px 0px 0px 15px; text-decoration: none; color: #ffffff; text-decoration: none; }
ul.dropdown li:hover { position:relative; }

/* header bar ends */

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