So I tried everything, I installed the new beta patch and it says wrong CD key but I'm able to play a few servers that both required and didn't require one. But the main problem is that my friend can't join the ones I can join and vice versa. He just recently bought Operation Arrowhead and I've had this for a year and been able to play games with my other friends with ease and no problems like such. And now when I try to launch a few servers I get this error message mainly and don't know what to do about it. I also get the message So if anyone can help me please tell me what I would need to do to fix this problem. And to keep in mind that I can't use steam to check the properties and change the things on that.
