I've had a couple of posts eaten that way when (IIRC) I tried to include a URL with too many/the wrong non-alphanumeric characters. I always tell myself to use a separate editor, or at least "Ctrl-A, Ctrl-Ins" before hitting the Post button, but I quite often forget.

Hitting the Forward or Back buttons on some of my keyboards while composing a post is another way to wipe it out. That doesn't cause an error, though.

HTH a little.

Cheers,
Scott.