That's most probably caused by the cache of your browser.
I deleted caches and the problem still the same.
I could not reproduce the issue in FF, Chrome or Safari. What's your environment?
I'm using firefox. I click the button, a loading icon will show at the center and then I will redirected to the xmlhttp.php page.
Check the console for eventual JS errors. Thread split.
I had the chance to analyze this error in detail and it turns out
ThunderBoard beta 6 needs an update.
