Hi,
Sorry for the issues you are having. I can help troubleshoot this with you.
I visited your site in IE11 and see the error happening.
I also tested some other sites and did not find the error on them.
I am getting this one error, but only in IE11:
Syntax Error File: pop-up.js, Line: 1, Column: 1
Not sure what is causing that error.
I would recommend running though our testing for conflicts guide and see if that helps narrow down where the issue is coming from:
Testing Conflicts With Themes and Other Plugins
Let me know what you find out and we can go from there.
Thanks