When the Facebook share button is clicked on a K2 article, some code is added instead of the intro text. I'm using the latest K2 install and Joomla 3.1.1 ... I've attached an image to illustrate the issue. the site is bluzink.com
This is comming from some twitter plugin. I do not remember which one was it, but I'm sure I've see this problem before. Please try disable anything twitter related and check after each if text is still there.