xyz: Try this. Go into your 'User CP', click on 'Edit Options', then scroll down to 'Number of Posts to Show Per Page' and change it from "Forum default" to either 25 or 50. Scroll the rest of the way to the bottom and choose "Save Changes". Finally, restart Firefox. That should take care of the unresponsive script boxes from popping up.

Perhaps the forum default could be changed from 1000 posts per page to something more sane, such as 25, 50, or 100?