In the "Ask a Question" box on the forum page you can't type more than 100 characters. But that's only explained when the page first loads AND you click on the page somewhere other than in that box (I'm running Firefox 6.0.2).
I suggest a better user interface. For example, add "(100 character maximum)" in the "Ask a Question" title bar. Or give a pop up of some sort when the user types character 101 rather than just deleting that character. That popup should provide the instructional text that this is really a subject line to find related posts and that you should click 'post' to actually complete the question you want to post.
I've posted in these forums before, so I don't know what's different today that made this confusing to me, but I can imagine it only gets in the way of newbies.