If there is an actual "issue" posting that you are sure it is the fault of the forum software, you should tell the people at Simple Machines
because they are the ones who wrote the forum software.
For those who are using IE or Safari try Firefox, it tends to run much better then IE or Safari does.
Also, when you press the back button (at least in firefox) the browser remembers the form state. Meaning as soon as you see your changes did not post press the Back button until you get to your post. There should be your post.