It looks like the upgrade to Joomla 3.1.4 can cause headaches for many extensions. If you haven't upgraded yet, I would hold off till 3.1.5.
Apparently the new release can cause problems with some "views":
Since upgrading our maintenance clients, we have found problems with:
As we find more, we will update this blog. In the near term, disabling these will allow the website to work properly.
In troubleshooting, I suggest looking at plugins that affect the front end rendering, like content plugins.
Know of other extensions? Please let us know in the comments.