So we are playing a 3 star map with 2vs2vs2vs2 mode with 2 being human players and the rest cpu players. The game is tunnelled through hamachi which might be the reason for this but I have never seen that happen before and we've had like 20-30 hours of Sins gameplay with hamachi without any problems. This however was the biggest game so far we tried to play.
After capping all the planets on the first star and heading to the second one I noticed 2 stutters that hasn't happened before, might have been the point where the gamesplit occured. As we both didn't notice it at first we started conquering the third mini star and then my friend goes "ooh, a starbase", and I asked where.... he replied with the name of the planet I capped first in the system "bellephone" or something. Anyways then I noticed his forces was just sitting in the spot and on both sides we could only see the other players forces moving between systems and then sitting there afterwards.
I'll include the savegame:
http://rapidshare.com/files/196662830/Save-MultiPlayer.rar.html
10 file download limit so don't download unless you need it, sorry but I really can't do much except provide the savegame of the gamesplit considering it has happened once in a day and we didn't notice it until after 10-20min. Saving and reloading doesn't fix it we are still both in our same splits afterward.