What causes users posts to not display and more tab to result in a 0?

Hi everyone

What causes clicking on the 'read more' tab to result in a 0 please? (See screen shot)

Plus, when you actually click on the title of the subject, Simon's comment (he's just a free user) disappears. Why is it doing this?

I log in as a different free user, and still cannot see this post. Login as an advanced user, and no issues with the more tab, Simons post appears (this is not Simons account, he is just a free user) and all seems ok. Yet the only negative rule in the free users group is that they can't access a URL which would allow them to list a business listing in the directory! Which is totally unrelated to being able to read a discussion!

I'm confused! What could be causing this please?