While looking about I came across this video for EA's next Publication Mercenaries 2: World in Flames. The video is in co-op mode so it maybe be hosted local as opposed to server based but maybe its some thing to do with the online code used by the EA family that is the problem?
Gametrailers.com - Hilarious Co-op Lag/Bug Part 2 by mistical
There is also a part 1 to the video but I thought this one looks better (and funny too!)
