Instructions
Load "Call of Duty 4" and connect to the PlayStation network.
Select the option to find a game so that you receive the error "Downloading Game Settings."
Shut down your PlayStation 3 from the switch on the back of the console.
Reset your router by unplugging it and waiting 20 to 30 seconds.
Reconnect the router and turn on your PlayStation 3.
Load "Call of Duty 4" again, and the problem should no longer persist.