I'm also getting the same problem. This is what I was going to post before searching, then I found this post.
I get the following error sometimes when making a most, or editing and trying to save it as a draft:
Your attempt to edit this post: “[insert title name here]” has failed.
Please try again. (<-- links back to the "post_new.php" page)
Any reason why? It's happening alot now. Sometimes it doesn't come back up when I actually do go back and re-publish it, but it's just a huge annoyance. I am at the latest wordpress instillation if this helps.