I'm having the same problem. I'm trying to make a post with no images or URLs, but get the error others have pointed out above.

I even pasted the text of the post into Word as unformatted, and then copied it back into the FT window to make sure there was no complicated formatting, and still get the error message.

I can't even post the message here to show you all! Help please? I'm not trying to get around a rule; I really can't figure out what in the world is going wrong.