Hi, couldn't see any pop ups in your page. But it might be possible that your site has been reported for some sort of problem or violation & visitors are getting a pop up from their own security/virus database. Might be worth getting a screen shot of the popup so we can see. (Alt & Prt/Scn).
Hi General. Why would they need a Sll certificate? They are using pay pal.
Just so i know for future reference. Thanks. 