Everything is said on the title.
My logs are full of (censored) :
PHP Fatal error: Internal Zend error - Missing class information for in /XXX/XXX/XXX/wp-content/plugins/like-button-plugin-for-wordpress/admin/gb_message.php on line 25, referer: http://XXX/XXX/XXX/options-general.php?page=fb-like-button
Saving the settings is hazzardous : sometimes yes, other time no.
THe like counter does not fit any counters of facebook pages.