WP is invalidating my XHTML Strict valid post

Hello, all went well from my migration from MT until I checked my site for validity.

My post was originally validated as XHTML 1.0 Strict. However, the content returned by http://ziphstric.com/blog/archives/2004/04/13/where-is-it-enumerated/ is not valid XHTML 1.0 Transitional.

I clicked to "Edit" my post in my WP blog and cut-and-pasted the content into a document and was able to confirm that the post content is valid XHTML 1.0 Strict.

In particular, the original is this:

</div>
</blockquote>

<!--
<blockquote cite="http://www.gpoaccess.gov/constitution/">
<p>

but WP is producing this:

</blockquote>
<p><!--</p>
<blockquote cite="http://www.gpoaccess.gov/constitution/">
<p>

By inserting the paragraph tags around the <!--, WP is messing up the validity of the subsequent information.

Here is a text file with the original post content (which when put into a compliant body results in a valid Strict document): wordpress-mangling-valid-xhtml-post-data.txt

On a more general note: Can I do something to prevent WP from doing anything to the post? It seems to take real carriage returns and create line breaks and new paragraphs. WP also makes a bunch of entity substitutions, some of which are incorrect.