Cleaning out my cookies in the browser didn't work for me, either, but logging out and logging back in has worked every time. I've noticed that the board won't let me log out sometimes, however, but if it won't let me log out, it's when I had no problem posting. When it will actually let me log out, I wasn't able to post. It's funny trying to log out over and over again and still being logged in, though. \:\)