I have funny result when try to displaying below html file. The browser like Firefox, Safari and IE (so far that I have tested) give me wrong result. Be careful when use <htmlElement /> when you need to define empty element, it is safer when you do it with <htmlElement></htmlElement>. Your browser may interpret differently 
This is my simple html file.
<table>
<tr><td>
<div id="table1">
<table border="1" summary="This table should be empty"/>here some text
</div>
</td></tr>
<tr><td>Some text</td></tr>
<tr><td>
<div id="table2">
<table border="1" summary="This is correct"></table>
<p>here some text</p>
</div>
</td></tr>
<tr><td>Some text2</td></tr>
<tr><td>
<div id="table1">
<table border="1" summary="This is correct because this table is empty"/>here some text
</div>
</td></tr>
</table>
<tr><td>
<div id="table1">
<table border="1" summary="This table should be empty"/>here some text
</div>
</td></tr>
<tr><td>Some text</td></tr>
<tr><td>
<div id="table2">
<table border="1" summary="This is correct"></table>
<p>here some text</p>
</div>
</td></tr>
<tr><td>Some text2</td></tr>
<tr><td>
<div id="table1">
<table border="1" summary="This is correct because this table is empty"/>here some text
</div>
</td></tr>
</table>
Output captured from firebug-Firefox extension
<div id="table1">here some text
<table border="1" summary="This table should be empty">
<tbody>
<tr><td>Some text</td></tr>
<tr><td>
<div id="table2">
<table border="1" summary="This is correct"/>here some text
</div>
</td></tr>
<tr><td><Some text2</td></tr>
<tr><td>
<div id="table1">here some text
<table border="1" summary="This is correct because this table is empty"></table>
</div>
</td></tr>
</tbody>
</table>
</div>
<table border="1" summary="This table should be empty">
<tbody>
<tr><td>Some text</td></tr>
<tr><td>
<div id="table2">
<table border="1" summary="This is correct"/>here some text
</div>
</td></tr>
<tr><td><Some text2</td></tr>
<tr><td>
<div id="table1">here some text
<table border="1" summary="This is correct because this table is empty"></table>
</div>
</td></tr>
</tbody>
</table>
</div>