母版页错误

最近做网站时使用到母版页，但我的页面在应用母版页时遇到一个问题：当第一次打开应用了母版页的页面时，无法切换到设计模式，如果切换会有错误：（母版页错误  网页包含附加到母版页是无效的标记 更正代码视图中的问题）
但是当我回到代码视图后，在任意一个位置稍作改动这个错误就不见了，例如，我可以在空白处敲一下空格键，并不修改任何代码，好奇怪！请问这是什么错误，麻烦高手们解答下！附上部分代码：
母版页：
<%@ Master Language="C#" AutoEventWireup="true" CodeFile="MasterPage.master.cs" Inherits="MasterPage" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>无标题页</title>
    <link href="App_Themes/MasterPage/MasterPage1.css" rel="Stylesheet" />
</head>
<body>
    <form id="form1" runat="server">
    
    <div class="header"></div>    <div class="nav">
    <ul >
  <li><a href="Default.aspx">首页</a></li>
       <li><a href="#">网站简介</a> </li>
       <li><a href="#">个人求职</a></li> 
       <li><a href="#">单位招聘</a></li>
       <li><a href="#">现场招聘</a></li>
       <li><a href="#">校园招聘</a></li>
       <li><a href="#">求职培训</a></li>
       <li><a href="#">在线留言</a></li>
       <li><a href="#">求职论坛</a></li>
       <li><a href="#">网站导航</a></li>
    </ul>
    </div>
    
    <div class="contentPlaceHolder">
    <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
    
        </asp:ContentPlaceHolder></div>
        
    <div class="bottom"></div>
    
    
    </form>
</body>
</html>普通页面：
%@ Page Language="C#" MasterPageFile="MasterPage.master" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" StylesheetTheme="Default" Title="无标题页" %><%@ Register src="SearchJob.ascx" tagname="SearchJob" tagprefix="uc1" %><asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<div class="outside"><div class="login_Notice_ResourcesDownload_CountPeople">
<div class="loginTitle">登录</div>
<div class="loginContent">
    <table cellpadding="0" cellspacing="0"  class="tbLogin">
       ..........省略部分代码 
    </table>
</div>
<div class="notice_ResourseTitle">
<div class="notice_title">通知</div>
<div class="notice_ResourseMore">
      ........省略部分代码
<div class="frendLinkTitle">友情链接</div>
<div class="frendLinkContent"></div>
</div>
</asp:Content>

解决方案 »

  1.   

    <%@ Master Language="C#" AutoEventWireup="true" CodeFile="MasterPage2.master.cs" Inherits="MasterPage2" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" >
    <head runat="server">
        <title>管理系统</title>
        <link rel="Shortcut Icon" href="53.ico" />
        <link rel="Book" href="53.ico" /> 
        <link rel="stylesheet" href="App_Themes/css/StyleSheet.css" />
        <meta http-equiv="refresh" content="1000" />
    </head>
    <body>
        <form id="form1" runat="server">
        <div style="text-align: center">
            <table border="0" cellpadding="0" cellspacing="0" style="width: 95%; height: 100%; background-color: #ffffcc;">
                <tr>
                    <td>                                </td>
                            </tr>
                                    <tr>
                                        <td style="text-align: center">
                                        </td>
                                        <td style="text-align: center">
                                        </td>
                                        <td style="text-align: center">
                                        </td>
                                        <td style="text-align: center">
                                        </td>
                                        <td style="text-align: center">
                                        </td>
                                        <td colspan="2" style="text-align: center"><div id="a" style="text-align: center"></div><script type ="text/javascript" >setInterval("a.innerHTML=new Date().toLocaleString()+' 星期'+'日一二三四五六'.charAt(new Date().getDay());",1000);;;;
    </script>
                                        </td>
                                    </tr>
                                    <tr>
                                        <td style="text-align: center">
                                        </td>
                                        <td style="text-align: center">
                                        </td>
                                        <td style="text-align: center">
                                        </td>
                                        <td style="text-align: center">
                                        </td>
                                        <td style="text-align: center">
                                        </td>
                                        <td style="text-align: center">
                                        </td>
                                        <td style="text-align: center">
                                        </td>
                                    </tr>
                        </table>
                    </td>
                </tr>
                <tr style="font-family: Times New Roman">
                    <td style="height: 61%">
            <asp:contentplaceholder id="ContentPlaceHolder1" runat="server">
            </asp:contentplaceholder>
                    </td>
                </tr>
                <tr style="font-family: Times New Roman">
                    <td align="center" style="background-color: #3a6d93;">
                                                    <br/>
                                  
                            </td>
                </tr>
            </table>
        </div>
        </form>
    </body>
    </html>