please can anyone explain to me what these problems mean on the W3c validator?:

Line 149, Column 6: XML Parsing Error: Opening and ending tag mismatch: body line 18 and div.
</div><!--end of container-->✉

Line 173, Column 7: XML Parsing Error: Opening and ending tag mismatch: html line 2 and body.

This is the page:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Diabetes Research Network - Home</title>
<link href="css/main_styles_new.css" rel="stylesheet" type="text/css" />
<link href="css/NiftyCube/niftyCorners.css" rel="stylesheet" type="text/css" />

<script type="text/javascript" src="NiftyCube/niftycube.js" ></script>
<script type="text/javascript">



<div id="container">
	<div id="header">
    	<img src="images/header.gif" alt="" width="950" height="187" />
    <div class="curvebox" id="topnav">
<!-- Google CSE Search Box Begins -->
<div id="search">
                <form id="searchbox_013124428372020973894:b5plyxttjne" action="http://www.ukdrn.org/search.html" class="googlesearch">
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          <li><a href="#">Home</a></li>
          <li><a href="about_us.html">About Us</a></li>
          <li><a href="#">News</a></li>
          <li><a href="#">Contact Us</a></li>
          <li><a href="#">Links</a></li>

	</div><!--end of topnav-->
    </div><!--end of header-->

    <div id="sidebar_left">      
      <div id="leftnav">
          <li><a href="#">Local Research Networks</a></li>
              <li><a href="#">Topic Research Networks</a></li>
              <li><a href="#">Portfolio</a></li>
              <li><a href="#">Industry</a></li>
              <li><a href="#">Patients</a></li>
              <li><a href="#">Jobs</a></li>
              <li><a href="#">Events</a></li>
              <li><a href="#">Training &amp; Education</a></li>
              <li><a href="#">Clinical Studies Advisory Group</a></li>
              <li><a href="#">Primary Care</a></li>
              <li><a href="#">Funding</a></li>
              <li><a href="#">The Team</a></li>
              <li><a href="#">Sitemap</a></li>
      </div><!--end of leftnav-->
<img src="images/ic_logo.gif" alt="" />
	    <div id="links">
	      <h3>Latest Links</h3>
	      <p><a href="#">Publications</a> - read articles published about the DRN in Diabetic Medicine and EDN.</p>
	      <p>The <a href="http://www.diabetes-stories.co.uk/index.asp">Diabetes Stories</a> website presents audio recordings of the life-stories of 50 people diagnosed with diabetes between 1927 and 1997. They talk with passion and humour about their daily lives and provide a unique oral history of what it was like to have diabetes during the twentieth century.</p>
	    </div><!--end of links-->

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              <p>Page controls</p>      
                    <li><a href="#"
                onclick="setActiveStyleSheet('Large Text','text'); return false;"><img src="images/control_larger.gif" alt="Increase text size" height="35" /></a></li>
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		<div id="updates">
          <div class="curvebox">
              <li><a href="#">North East London LDRN</a> - newsletter added</li>
        <li><a href="#">Patients</a> - Council of People Living with Diabetes (CPD) - Volunteers Required </li>
		</div><!--end of updates-->
		<div id="jobs">
			<div class="curvebox"><h2>Jobs</h2>
                <li><a href="#">Cross Network Research co-ordinator</a>, UKDRN CC </li>
                <li>Thames Valley LDRN - Diabetes <a href="#">Research Nurse</a> </li>
                <li>North West London LDRN - Senior Research Nurse and<a href="#"> Research Nurse/Clinical Trials Officer </a></li>
		</div><!--end of jobs-->
		<div id="email">
		  <div class="curvebox"><h2>Email Updates</h2>
		  <p>Would you like to be notified when changes are made to the DRN website?</p>
            <form action="alerts_emailer.asp" method="post" class="alertform" id="alert" onsubmit="MM_validateForm('name','','R','Organisation','','R','email','','RisEmail');return document.MM_returnValue">
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  <div id="content">
    <div id="intro_shadow">    
      <div id="intro"><h1>Welcome to the Diabetes Research Network</h1>
        <p>The primary goal of the UK Diabetes Research Network (DRN) is to achieve benefits for people with diabetes, or at risk of developing diabetes, through excellence in clinical research. The aims of the network are:</p>
          <p>&quot;to facilitate the conduct of randomised prospective trials and other well-designed studies of diabetes, including those for prevention, diagnosis and treatment&quot; </p>
        <p>To read more please visit our <a href="#">about us</a> page.</p>
      </div><!--end of intro-->
    </div><!--end of intro_shadow--> 
    <div class="section">
        <h2>Novel interventions for the complications of diabetes - Diabetes UK invites research proposals</h2>
        <p>Diabetes UK is seeking research proposals in the area of Novel interventions for the complications of diabetes. </p>
        <p>This call is to support ‘first in human’ trials and ‘proof of concept’ studies, and excludes proposals based on in vitro or model systems. Interventions may include: drug or cell based treatments; devices and instruments; surgical, dietary, or novel applications of existing therapeutics</p>
        <p><a href="#">Read full details</a></p>
    </div><!--end of section-->
  <div class="section">
        <h2>Type 2 Diabetes - National clinical guidelines updated (primary and secondary care)</h2>
        <p>The National Collaborating Centre for Chronic Conditions (NCC-CC) has produced the latest clinical guidelines for type 2 diabetes in primary and secondary care. The updated guidelines will be of particular interest to healthcare professionals.</p>
        <p> <a href="#">For further details - Leaflet and order form</a> </p>
  </div><!--end of section-->
      <h2>Launch of a new patient resource which highlights the importance of diabetes research</h2>
	  <p>A new <a href="#">DVD and website resource</a>, launched today by the National Institute for Health Research (NIHR) Diabetes Research Network, aims to encourage patients to get involved in diabetes research. </p>
  </div><!--end of content-->

</div><!--end of container-->

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	      <li><a href="#">About Us</a></li>
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		<p>Copyright &copy; Diabetes Research Network 2008</p>
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Many thanks