Fatal error: Class 'Facebook_User' not found

I keep getting this fatal error every time I activate the Facebook plugin, and I try to acces the author page. Exmaple. http://www.sample.com/author/name

Fatal error: Class ‘Facebook_User’ not found in /home/content/67/8963367/html/websitename/wp-content/plugins/facebook/open-graph-protocol.php on line 336

However, when i deactivated it works perfect.

http://wordpress.org/extend/plugins/facebook/