Forums auto hide

Recently we launched our forum and within like a months time or something, some of the forums were not getting seen from the main forums page. We tried a work around to make them visible. What we did was we added a topic and then set the visibility to hidden. Now that sure made the topics visible but I doubt if this is a better alternative to this workaround.
Has anyone encountered this 'forum auto hide' error before? Is there a solution to it.

Thanks in advance people.

Hey Bruce,
Thanks for your reply, but I guess the 'Show Topics from xxx time' was not exactly what I am looking for. Here is the problem.
There are some forums on my page that have no topics (since the forum is new). These forums are not seen from the main page(suddenly, as in they were visible few days back), though I have created them and I see them from the control panels forum management area as well as the "Forum jump" option placed on the topics page.
Please check out the behavior of the same at our forum site. Anyway, to tackle this situation I have created new blank topics with just a "." as subject and hid them (for the time being unless I get a solution for the same).

Is there a solution to this problem?
Thanks in advance.

Tried that but still no luck . Any other suggestion? why this would be happening? This is really surprizing. Even if it was a permission issue why would the forum topic be visible in the "Forum Jump" option and not on the main forums page?