In case your WP_CONTENT_DIR location is not default…

I have the following in my tf_display.php

Line 35:

wp_enqueue_style('tfg_style', '/wp-content/plugins/twitter-facebook-google-plusone-share/tfg_style.css');

Replace to:

wp_enqueue_style('tfg_style', plugins_url('tfg_style.css', __FILE__) );

HTH someone.

http://wordpress.org/extend/plugins/twitter-facebook-google-plusone-share/