How do you access the forum?
Best is to take this link:
http://www.larian.com/ubbthreads/ubbthreads.php (maybe you can bookmark this link?)
I know it sounds silly, but I should have a look at the frame-thingie from the <img src="/ubbthreads/images/graemlins/beyond.gif" alt="" /> website, I think the problem is somewhere over there.
But I lack some time now...
With which browser are you working?