there is something wrong in your file social-articles.php!
There you have some code on line 213:
This snippet is responsible for a misunderstanding of the SSL Certificate. Please take a look to my screenshots:
Screenshot 1 with your plugin activated in Opera
(shot says: Wrong Certificate name. Certificate does not match with hostname)
Screenshot 2 with your plugin deactivated in Opera
Same is valid for Internet Explorer. Firefox let it through but has a hint within the certificate information, same for Google Chrome.
Please check your plugin because it has a conflict with SSL Certificates and gives wrong information to the user.
PS: Great plugin, I made the German translation for you weeks ago. It took me weeks to find out whats wrong with your plugin and I had a huge conversation via E-mail with my hoster ;-)