Even if it says that it validates in it's description and in the footer of the theme, well it doesn't.
To fix this you have to edit the node.tpl.php and block.tpl.php so that instead of <p class="content">...</p> it reads <div class="content">...</div>
Also on page.tpl.php you must have to move the if statement before the ul tag (and of course endif after the </ul>) or it will not validate when you don't have a breadcrumb.