Hey all i have finally figured out a way to fix this stupid error that ACTIVISION cant even work out the useless C****.

ok, turn off your ps3 at the main switch located on the back of the ps3 (near power cord) than reset your router while ps3 is still switched off. after your router has rebooted turn on your ps3 and you should be able to play MW3

this just worked for me and 2 of mates about 3min ago 6:33pm EST 26/09/12

Like or comment on this thread if this has helped.