It's been 24 hours now that I cannot connect. I can see from others that have the same issue. It's funny because some people keep asking "Have I got banned" ... (actually it's a good tactic to get all cheaters into the surface lol).
Anyway, I also have this problem and yes, I haven't spent €60 to cheat. I get this error "The Call of Duty: Modern Warfare 3 server is not available at this time. Please try again later or visit http://www.callofduty.com/mw3/status for updates".
I have checked the status page and surprise-surprise, everything is up and working. But the game for which I paid for out of a sudden stopped working! I have been playing with no problems since release date but as of yesterday, not any more.
If this is a known issue just let us know to wait. If it's something that we can do, also let us know. Just don't let us live the unknown.
Anybody else with this issue?