I wrote a new post (over several minutes, so the auto-save did its thing). I hit the publish button and got that popup that I get when trying to close a "write post" window about nagivating away from the page. (see http://trac.wordpress.org/ticket/6711 )
Of course I hit cancel. Then I was back in the post. Somehow, I got the idea to cut and paste all my text over to a word file, just in case. Then I decided to peek at the HTML code for the post.
The post disappeared! The HTML window came up but the text area was blank. The title and slug are intact, along with my tags and categories. But the text is gone. I went back to visual mode and the text is still missing.
I have checked my blog and the post did not publish. The post is listed as a draft, but the text is still missing (it's no longer blank though...the only thing there is a close-linebreak marker.
Trying this again...I pasted the text back into the draft. I fixed a couple of formatting things that were lost (took several tries; it messed with my code as a tried). I went into HTML mode; text was still there. Went back to Visual mode; text was still there.
I tried "publish" again and this time it worked.
What a terrifying bug! I've never lost a post before. In fact, the older versions of WP were so good that if my browser or computer crashed while I was in the middle of a post, even if I never hit "save," there would be a draft waiting for me with everything but the last couple of seconds.