Okay, so if the game was working this morning, and now it's not, despite a reinstall (which I guess means all my message and audio options are now returned to default settings), what, -precisely- do I need to do to get the game to allow me to play Ironman? If there are ports that may have magically become blocked in the last three hours, how do I determine that? Is this a Steam problem or an EUIV problem?
If it helps you feel better, I've encountered the same exact issue. This morning and this afternoon it was working perfectly and now Ironman mode cannot be enabled as of an hour or so ago. Tried reinstalling, deleting the EU4 documents folder. Another thing I've noticed is that it kinda "hangs" on the "creating checksum" at startup.