I just noticed this happening today as I was going to queue up a number of posts for next week...
I go to post/add new and I am presented with the editing screen. I enter my title, past my text from my editor and click on Save Draft and after waiting a few seconds I am presented with a blank edit page again.
I have turned off all plugins and tried again - same result.
I changed themes to the default 2012 them - same result.
I also notice when I display all of the posts I see an autodraft and it will not let me trash it.