I just made a trial forum, to see if the freebie forums work better, and it certainly seems to.
Here's the link:
http://www.phpbber.com/phpbb/index.php?mforum=btrial
It's really fast, and the only error I've gotten so far is the "You cannot make another post so soon" one.
edit: it's full of advertisements, though. Maybe that's why it works better, maybe showing ads to people pays more than hosting messageboards, and thus gets better support?