Have you got the latest version of template, K2 or social plugin ?
Because in January 2013 many Facebook like buttons stopped working due to some changes internally on how the Like button functions with respect to content restrictions, publishing updates and interactions with users. Many sites using the HTML5 or XFBML methods to share content saw a link labeled as “Error” on their pages. When they clicked on the error, they get a small window that states:
The href URL must be absolute.
Read here:
http://www.hongkiat.com/blog/fb-href-absolute-error/ If you’re not using PHP or CMS, but rather have your share code embedded directly in the HTML, make sure you use the full path of the URL (
http://www.yourdomain.com/page).
This should take care of the error message you’re seeing.