So if your a cod 4 player and like to get a game now and again you might notice every time you try to play it you get a confirm screen, and you can never get past it?
I figured out how to bypass this and get to the multiplayer:

1. First restart your ps3 and sign out of psn
2.Turn off your router for the internet
3.Load up cod 4 and you shouldn't get the confirm screen
4.Once your in the menu go to multiplayer and then turn your router back on
5.Sing into Psn and you should still be on the menu, select a game type you want then it should find a lobby

Ps there isn't going to be a lot of people on it and you might be waiting a while to find a lobby and yes you do have to do this every time you want to play cod 4 which is a bummer =( hope this helps =)