FCKeditor is butchering my code

FCKeditor is reformatting my HTML code, but is doing so in a completely incorrect way.

For example, let's say I have FCKeditor installed on a news site where authors are entering story copy. Now, let's say I want to float a box on the right of my article. Assuming I have "div" defined in the "ProtectedTags" directive, I click on Source and hand enter the following...

<p>Some text before</p>
<div class="floatBox">
<h2>Some heading</h2>
<p>Some text that someone would be interested in.</p>
</div>
<p>Some text after</p>

Saving the article, and reloading the editor, I see that FCKeditor has mangled the hell out of my code as follows:

<p>Some text before</p>
<p>
<div class="floatBox">&nbsp;</div>
</p>
<h2>Some heading</h2>
<p>Some text that someone would be interested in.</p>
<p>Some text after</p>

So my question is how do I stop FCKeditor from doing this? It's treating a div tag as if it were a formatting tag, not a peer to a p-tag. I'm about to revert to a year-old version of the editor that doesn't do this atrocious reformatting.

Thanks in advance.

-Steve