I was in the middle of playing my single player playthrough on a slim 250gb US region PS3, when a buddy of mine shot me a multiplayer invite. I had never played multiplayer before so I had never entered the online activation code which I'm guessing is what prevented me from joining him at that time. After trying to join his session & failing I went to go create my own session to see if he could join me only to find out there was an online pass activation code required, but my brand new copy of the game I bought from Walmart, didn't ship w/ a manual thus no code, so I had to buy one from the PSN store. Aggitated... So after I purchased the code, played a few rounds w/ my buddy, I went to go back to my single player game, to find it still shows as playing 9 hours & 10 minutes, but my game progress is 0% w/ 0 collectibles found on the mission prologue. Really aggitated... Luckily I created a manual save @ about the 8 hour mark so I didn't lose everything, but you can see there is clearly a problem here.