(Yes, I know, I should be upgrading, I'm on dialup and way behind)...
Seems I'm not the only one having a problem with kitchen sink.
I had the tinymce advanced plugin, it worked fine for awhile but suddenly it was kind of on-again, off-again; the regular kitchensink was directly affected. I blamed my dialup ("oh, it isn't loading right, this crappy dialup"). But, I went and deactivated the plugin, but it isn't helping. "Visual editor" does nothing but show my html AND a cluttering of unwanted / unneeded tags.
<joke>Maybe my Cat's ate the mice? </joke>