We discovered that there were some core changes in the 2.5.11 version of Joomla that affects things displaying on the front end and also affects saving categories and in some cases events. We are putting the fixes together right now and will post an update when it is available for downloading.
We posted a new update on our website today. It is very important that you download it if you are using Joomla 2.5.11. Core files changed in this version and it required us to modify many scripts to deal with their changes.