WordPress database error

I am using the latest version of WP and MailPoet 2.6.9
My website was getting real slow and when I checked the error logs, I saw many of such entries –
[29-Jul-2014 13:34:05 UTC] WordPress database error Duplicate entry ‘2-248’ for key ‘PRIMARY’ for query INSERT INTO wp_wysija_user_list (user_id,list_id,sub_date) VALUES (248,2,1406640845) made by require(‘wp-blog-header.php’), require_once(‘wp-load.php’), require_once(‘wp-config.php’), require_once(‘wp-settings.php’), do_action(‘init’), call_user_func_array, oa_social_login_init, oa_social_login_callback, do_action(‘user_register’), call_user_func_array, WYSIJA::hook_add_WP_subscriber, WYSIJA_model->insert, WYSIJA_model->save

Can you tell me whats wrong and what should I be doing next?

https://wordpress.org/plugins/wysija-newsletters/