Problemas con XHTML 1.0

[Reynier]

Código PHP:

  <table width="99%"  border="0" cellspacing="0" cellpadding="0" class="table1">
    <tr>
        <td width="100%" align="center" class="topnav3">Confeccionado con</td>
    </tr>
 
    <tr>
        <td class="td image" align="center"><a href="#" onClick="javascript:window.open('http://www.mysql.com');"><img  align="middle" src="themes/images/powered/mysql.gif" border="0" class="cursor"/></a></td>
    </tr>
    <tr>
        <td class="td image" align="center"><a href="#" onClick="javascript:window.open('http://www.php.net');"><img  align="middle" src="themes/images/powered/php.gif" border="0" class="cursor"/></a></td>
    </tr>
    <tr>
        <td class="td image" align="center"><a href="#" onClick="javascript:window.open('http://smarty.php.net');"><img  align="middle" src="themes/images/powered/smarty_templates.gif" border="0" class="cursor"/></a></td>
    </tr>
 
    <tr>
        <td class="td image" align="center"><a href="#" onClick="javascript:window.open('http://www.bradburry.com');"><img align="middle" src="themes/images/powered/topstyle.gif" border="0" class="cursor"/></a></td>
    </tr>
</table>
</td>
                
                <td width="603" valign="top" class="lefline">
                                    <form name="registro" id="registro" action="" method="post" enctype="multipart/form-data">
                    <table width="100%"  border="0" align="center" cellpadding="0" cellspacing="1" class="table">
                      <tr>
                        <td colspan="2" align="center" class="th">Registro de nuevo usuario</td>
 
                      </tr>
                      <tr>
                        <td colspan="2" align="center" class="topnav">Datos Obligatorios</td>
                      </tr>
                      <tr>
                        <td width="31%" align="right">Nombre de Usuario:</td>
                        <td width="69%"><input name="uname" id="uname" type="text" size="25" maxlength="25"/> <span class="info" title="Tu Nombre y Apellidos"><img src="themes/images/help.gif" align="middle" border="0" class="help" /></span></td>
 
                      </tr>
                      <tr>
                        <td align="right">Correo Electr&oacute;nico:</td>
                        <td><input name="ucorreo" id="ucorreo" type="text" size="50" maxlength="250"/> <span class="info" title="Correo Electr&oacute;nico v&aacute;lido, de lo contrario no podr&aacute;s hacer uso del Portal"><img src="themes/images/help.gif" align="middle" border="0" class="help" /></span></td>
                      </tr>
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                        <td align="right">Nick:</td>
 
                        <td><input name="unombreusuario" id="unombreusuario" type="text" size="35" maxlength="35"/> <span class="info" title="Este ser&aacute; el nombre de usuario que te identificar&aacute; en el Portal"><img src="themes/images/help.gif" align="middle" border="0" class="help" /></span></td>
                      </tr>
                      <tr>
                        <td align="right">Contrase&ntilde;a:</td>
                        <td><input name="uclave01" id="uclave01" type="password" size="35" maxlength="250"/> <span class="info" title="Cotrase&ntilde;a: trata de que la misma sea alfan&uacute;merica, o sea, contenga letras y n&uacute;meros"><img src="themes/images/help.gif" align="middle" border="0" class="help" /></span></td>
                      </tr>
                      <tr>
 
                        <td align="right">Repetir contrase&ntilde;a:</td>
                        <td><input name="uclave02" id="uclave02" type="password" size="35" maxlength="250"/> <span class="info" title="Contrase&ntilde;a igual a la anterior"><img src="themes/images/help.gif" align="middle" border="0" class="help" /></span></td>
                      </tr>
                      
                      <tr>
                        <td align="right">C&oacute;digo de Confirmaci&oacute;n:</td>
                        <td><input name="usecuritycode" type="text" id="usecuritycode" size="16" maxlength="16"/></td>
 
                      </tr>
                      <tr>
                        <td colspan="2" align="center" class="topnav">Datos opcionales</td>
                        </tr>
                      <tr>
                        <td align="right">Pa&iacute;s:</td>
                        <td align="left">
 
                        <select name="upais" size="1" id="upais" onchange="javascript:return switchImage();" onkeydown="javascript:return switchImage();">
                                                                              <option value="Afganistan">Afganistan</option>