Uh oh
I tried to make a test post and experienced the same thing. This happened to a handful of members a long time ago, after a server outage corrupted some of the blogs. Given the date of your last post, I think yours was affected as well
Would you like to start a new blog? We can delete the old blog and let you sign up again. You can go to
http://www.3fatchicks.com/diet-blogs/wp-blogsignup.php and create a new blog that is attached to your existing blog user account (make sure you are logged in). However, if that one doesn't post for you then we would need to delete your blog user as well, and let you start completely from scratch.
I'm sorry for the trouble!