¿como puedo arreglar esto??
Line 174, column 15: end tag for "table" which is not finished
</table>
Most likely, You nested tags and closed them in the wrong order. For example <p><em>...</p> is not acceptable, as <em> must be closed before <p>. Acceptable nesting is: <p><em>...</em></p>
Another possibility is that you used an element (e.g. 'ul') which requires a child element (e.g. 'li') that you did not include. Hence the parent element is "not finished", not complete
En html esta asi:
<div id="contenidoprin">
<table>
<thead class="titulo">
<tr>
<th class="titulo">HISTORIA</th>
</tr>
</thead>
</table>
</div>
Una cosa que tengo hecha en flash tampoco valida, tiene arreglo?