Often times when it does not post, I will see a tan colored box at the top of the page that says working and my cursor will show busy, if it does it to long, I will open another window and come into the page again to find out, it did actually post.
Also, sometimes when I click on a topic, it will give me the working box and I have to refresh the page, it is like it is still having trouble updating the database or at least completing the database update, so you have to manually refresh the page.