registration error

Hello,

we've started experiencing registration errors. We use the user registration with activation email. After a cache purge or Apache restart the user registration works once. On a consecutive attempts the form gets submitted with no warnings but results in a generic page with error "Sorry, but there are some errors in your registration form". The following outputs to Apache log:

[Wed Dec 11 12:48:29 2013] [error] PHP Warning:  Missing argument 3 for SocialDispatcher::trigger(), called in /var/www/plugins/user/easysocial/easysocial.php on line 187 and defined in /var/www/administrator/components/com_easysocial/includes/dispatcher/dispatcher.php on line 80, referer: /administrator/index.php?option=com_easysocial&view=users

[Wed Dec 11 12:50:24 2013] [error] PHP Notice:  Undefined index: es-fields-69 in /var/www/media/com_easysocial/apps/fields/user/cover/cover.php on line 76, referer: /unity/registration

[Wed Dec 11 12:50:24 2013] [error] PHP Notice:  Undefined index: es-fields-67 in /var/www/media/com_easysocial/apps/fields/user/cover/cover.php on line 76, referer: /unity/registration

[Wed Dec 11 12:50:24 2013] [error] PHP Notice:  Undefined index: es-fields-54 in /var/www/media/com_easysocial/apps/fields/user/joomla_timezone/joomla_timezone.php on line 106, referer: /unity/registration

[Wed Dec 11 12:50:24 2013] [error] PHP Notice:  Undefined offset: 1 in /var/www/administrator/components/com_easysocial/tables/registration.php on line 162, referer: /unity/registration

Any clue to a solution is greatly appreciated.