I am just going to post this because I have been getting the same problem. The forums are acting up again, and some people are hitting the submit 2 or 3 times before it goes. I have a suggestion for all you people that this is happening to.

If you see the progress bar in your browser going really slowly, and it doesn't seem to be submitting, try pressing the "Preview Reply" or "Preview Post" button before you hit the submit button again. This will allow you to see the previous posts below the input box and you can see if your post was actually posted. If not, then you can press the submit button again, but if it is there, just click on the link at the top because the post is there, it just never told you that it was submitted.