Sorry to hear about the trouble... if you know which event is causing this issue specifically, can you provide the script text for this POPUP event?
It is hard for me to know what this might be without seeing it, and especially so if it is an exactly repeatable issue as it should be pretty straight forward to track down.
It is difficult to know which script this message comes from because the message does not always happen at the same turn.
I don't use any image other than the one in the vanilla version. i only use #POPUP= juste below #NAME=
Could you try to see if it happens with the default campaigns as well? This will tell me if it is perhaps a custom campaign or something with your computer etc.
it always happens during the same turn but never at exactly the same stage of the turn.
I made the backup just from the previous round so if I send you the backup you could test on another computer.
the backup file is 38000 K I don't know in what form to send it to you.