PopUp Pro Creating PopUp when Not Called and Preventing Transaction

I have been using PopUp Pro to allow me to force people to login before they purchase courses in my CoursePress based website. This last week I had a user say that she was unable to purchase a course. She was already logged in and went to purchase a course and a blank white pop up showed up on the screen and wouldn't let her proceed. So I tested and I found the same thing. When I am logged in and click on Courses and then click on Details on a course to purchase it I get the white blank pop up. I checked my PopUp Pro settings and they are set correctly to only create the pop up if the user isn't logged in.
Thanks!
Tony