If you only allow it once, the course can open, but the course may not be able to post your final score to the LMS, which often requires a second pop-up to open in the background. In Internet Explorer, you may receive a message asking you to Allow Once, Allow Always, or don't Allow. Following is how to address your pop-up blocker in each kind of browser: If you can't open the course, you may get a warning that the browser has blocked a pop-up, or if the course opens but shows only a blank screen, you may be experiencing a pop-up blocker. Web-based courses use pop-ups to open the content of the course and to communicate with the Learning Management System.