BF4 has been out for just over a month and a half, and anyone following it will be aware of the nightmare DICE have been trying to dig themselves out of, and the Class Action Lawsuit being filed against EA!
When starting Multiplayer, the game downloaded the Multiplayer Update 4, installed itself and played. Then lagged, crashed mid game, and finally started locking up the entire console mid session losing all progress.
Raging, I took to Google and after a while finally resolved my issue. You need to MANUALLY INSTALL UPDATES 1,2 AND 3!