@SydneyAHarris - First sorry to hear that, but I have to say that it has been heavily tested on WP 4.5.2+, even our live site uses that combo. Can you check your PHP error logs? Sounds like possibly the Popup Maker plugin files have become corrupted, Maybe try deleting them manually then reinstalling fresh.
Your PHP error logs during the time you get server errors will tell us exactly what is happening.