I know this is a common problem for other users and this has been reported before.
Often, if I edit an existing post, when I resubmit it, the spinning cogs appear but don't go away. What I do then is to close the spinning cogs screen by clicking on the top right hand little cross of that screen. This takes me back to the posting screen. Because I know the re-edited post has in fact been posted, I don't try to repost the post. Instead I close the posting screen by clicking on the top right little cross of that screen.
This takes me back to the thread screen which still shows the original post. I then refresh the screen which then shows the revised posting.
I use Firefox v3.6 and Windows XP Professional service pack 3.