Xbox 360 online issues? (games splitting into two)

[Houdini42]

Me and a friend play coop a lot on Ruse (us two vs ai) online and nearly every game halfway through it'll "split" into two different games. We end up talking and he says there's units behind me, and I say what units? Or even more frustrating I've wiped out the enemy bases and he goes they are still there? Its even worse if I win the game, he gets stuck in game and when I leave (after winning) it says I've surrendered? I've had a look and I can't find any reference to this problem.

Its an insanely odd bug and I was wondering if anyone had any insight into it?

Thanks.