WordPress creates invalid XHTML in some scenarios when a DIV is used

[duanestorey]

If you insert a DIV into the post, WordPress sometimes seems to insert an extra closing P tag, which causes XHTML validation to fail. The test content I used was:

<div id="test">
This is some test content.

This is some other content.
</div>

And the extra closing P comes after the first sentence.

[Denis-de-Bernardy]

see #3833 and related tickets