Desynchronization in the multiplayer mode of Heroes of Might and Magic V: Tribes of the East.

It happened to me once; I was playing through Hamachi with an opponent, and at some point, the connection started to degrade, but there was no disconnection. Then, the opponent told me to finally set up my units because he had attacked me, but I couldn't even see him on the map. In the end, we had a 2-3 day desynchronization, but we couldn't load the game.
I think there was a similar problem on Ubi.com a long time ago, but I don't know how they solved it or if they even solved it at all.
It hasn't happened again since.