Pop up problem

I recommend cycling your other plug-ins and your theme to check for a conflict.

Disable all plug-ins and switch to a default theme, then re-check each time you re-activate something on the site, starting with your theme.

This will help isolate what is causing the conflict, which is important for trying to debug this. Also, try being logged-in as a user with lower permissions (e.g., a subscriber), to see if it happens the same way in that situation.