I had this a lot before the patches (my gold subscription is expired atm). I was playing the game through for a second time in co-op with a friend, and one day we just couldn't connect any longer. VERY frustrating. Once in a blue moon it would work, the rest would be 'unable to connect' etc. Since it's the only game i'm interested in playing on xbox live I won't be renewing my subscription for a fair while!