CKEditor does not work in https mode

Hi,
We are using CKEditor for a long time and it has been working great. We are using latest 4.3 version. Recently we moved our application form http to secure https mode and now the editor is not working with IE10 and IE11 browsers until I press "Show all Content" button and refresh the page 3-4 times. I get the following javascript error.

"Unable to get property 'remove' of undefined or null reference". Below javascript code I am using to replace simple textarea with rich text editor.

CKEDITOR.replace( 'txtEmail',
                    {
                        enterMode        : Number(2),
                        fullPage : true
                    });

Please help me to solve this issue. Thanks