BF3 coop does not start

[mrshot]

Hi, I am facing issue with the coop mode. I cannot play with my friend, it's connecting like always but when there is black screen displayed - only "loading..." animation is visible and after a while game closes unexpectedly. We both are trying to play on PC, it was working earlier, something strange happens, as I am reading on the Internet - a lot of people had the same issue and no clarified solutions still...
Any tips? Tried solution from https://answers.ea.com/t5/EA-General-Questions/Battlefield-3-game-does-not-start/m-p/5189814#M194966 but same effect :/

[south0fheaven]

I think it's a problem if one person has the Origin version of BF3 and the other a Steam version. I had this issue quite a few times and it seemed to always be the case unless it was two Origin BF3 players trying to do Co-Op it just doesn't work like it's out of sync or not compatible with the Steam version.