WP changes my class names

WP is change some of my class names to <div> </div> The following microdata, shortened example below:

<div class=”book”>
<div itemscope itemtype=”http://schema.org/Book”&gt;
<div itemprop=”name”><h3>A Most Haunting Castle</h3></div>
<div itemprop=”description”> </div>
<div itemprop=”author” itemscope itemtype=”http://schema.org/Person”&gt;
CHANGES TO…

<div class=”book”>
<div>
<div>
<h3>A Most Haunting Castle</h3>
</div>
<div></div>
<div>By: Bob Mann</div>
<div>Published: 09/03/2012</div>
<div>Edition: 1st</div>

Can anyone offer some guidance on this – any link that explains this oddity.
Thanks – Mike