It is hard to diagnose the problem when I haven't experienced it before and you didn't really give much information.
Is there anything in the error log?
When clicking on a topic are you in that topic (but it is displaying all the stories) or are you being redirected back to the home page?
How many topics do you have and are any of them child topics?
Is your site multilingual?
One of the Geeklog Core Developers.