Crashing after a few days of play [PC] [MP]

[BajanPez]

As title says, I'm hosting a multiplayer game with a friend. I have all DLC, he has none. We started a game with two ruler designed Counts, at first it would crash before january ends after I reinstalled it crashed at april 24th.
Playing on the latest version and original checksum of the version.
I can provide what the microsoft crash reported if needed. (Was BEX Event)
Thanks for all the help.

 

[AndrewT]

Was this a game crash, or an out-of-sync error?

Does it matter who hosts?

Does it happen if you don't use the Ruler Designer? If you use no DLCs at all?