Check that you are connected to Xbox live. You should go to Xbox.com/support for help.
Your disk might be scratched, or you console and/or computer is broken
If you're on the xbox, you need xbox live gold, and an internet connection. If you're on pc, just a connection, and same with ps3
You cant
yes you should if you want to follow the story line in the campaign mode
yes because theyll get bullied at school cos they cant play
yu cant only in mw3
No, you cant. Your only able to play buddies on split screen
Depends which modern warfare game you mean if its the first one you cant play co-op but on modern warfare 2 you can play with another person but only on special ops. You will need to get a second controller, use system link or play with people online(Xbox live/PSN).
Unfortunately, you cant because your penis is too small.
No
nope =D
You play it.
Not really. The campaign will still not make sense, even if you played the first Modern Warfare.
Yes, a keyboard is necessary to play Modern Warfare 2 on PC, however you cannot use a keyboard to play Modern Warfare 2 on PlayStation 3 nor Xbox 360.