As An Aside, A WordPress mod_security Fix 

If all of a sudden your blogging client stops being able to send posts to your blog, it's possible your host turned on mod_security.

Try adding this to your .htaccess file:

	
	<files xmlrpc.php>
		secfilterengine off
	</files>

(hat tip to http://www.red-sweater.com/forums/viewtopic.php?id=269)