I started getting this error a few days back.
I exported posts in xml, deleted WP, installed brand new, imported .xml file with posts and attachments, the only this that I did - set permalinks to "Post name".
I changed url, updated the post. I still get the same error.
Here how it looks like : http://russianartsales.com/%EF%BB%BFsurrealists-and-%EF%BB%BFsurrealist-painting/
I searched. Found that that might be because of byte order mark. I installed the script to delete that from all my files initially. Did not help.
Any help would be appreciated.