Hi again Dave,
Just had another look round, - your ai/services.html also links to Clients.html with an uppercase 'C'.
Also, your pages are also linking to menu.css (and ai11.css) and menu.js files in two different locations.
What I think it would be worth doing to get rid of any uncertainty, is re-doing the code between the head tags by replacing what you have on each page with:
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Accelerated Innovators</title>
<link href="ai11.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" src="CSSMenuWriter/cssmw/menu.js"></script>
<style type="text/css" media="all">
<!--
@import url("CSSMenuWriter/cssmw/menu.css");
-->
</style>
<!--[if lte IE 6]>
<style type="text/css" media="all">
@import url("CSSMenuWriter/cssmw/menu_ie.css");
</style>
<![endif]-->
</head>
and replacing your menu code on each page with:
<ul class="level-0" id="cssmw">
<li><a href="index.html">Home</a></li>
<li><a href="services.html">Services</a></li>
<li><a href="clients.html">Clients</a></li>
<li><a href="about.html">About Us</a></li>
<li><a href="jobs.html">Jobs</a></li>
<li><a href="contact.html">Contact Us</a></li>
</ul>
and make sure that you have your pages (including 'contact.html'), your CSSMenuWriter folder and the ai11.css file all in the same directory.
I like the nice clean style of your design.