It sounds like when you did your last vbulletin upgrade, you didn't upgrade your style templates. Go to - vboptions > General Settings > Add Template Name in HTML Comments > set to Yes and then go back to the page where you clicked unstick and look at the page source. Find the <form> that was supposed to perform the action. Get the name of the template that contains the form. Go to edit that form and View History > Compare and you should see a line about a securitytoken highlighted. Add that line to your template.