Alright so, my friend and me were checking about the game load issues and we figured something out.
We were sharing the save game archives in the game folder located at My Documents, and we even were able to load eachother's saved game as the server, but keeping always the same character as before (for example player one hosts, so he automatically is Cooper, and player two joins and picks O'hara for example, so with the savegame archives from the host, player 2 can host the same game at the same point it was saved before being O'hara instead of automatically being Cooper as ussual).
But, no matter who hosts always the the client (the one whos not the server) will get this error "ERROR: MPF_rCREATETASKSET calls fails - BIS_missionScope is nil" and his, i don't know how to call it, the objectives screen, gets corrupted and shows like the "key name" of the mission, something like obj followed by the key word of the mission (for example: objGorka, or objLagushina or whatever her name was). And this ends with the mission entirely bugged for the client, who will be unable to see or accomplish any objective by himself.
So we guessed that there's a bug when saving the game, something like it doesn't save the game properly for the client. It looks like it takes a lot directly from the single player campaign, and this may end saving the states only for the "player 1".
We hope some of the guys from BIS could find this helpful and, of course, try to solve that bug. Thanks