If you are getting a error most likely like this one, it means Combat Arms USA and EU is patching right now as we post and speak. How can you stop it? You can't just wait for it to be done patching and have fun with your friends.
What You Can Do: Google Google some fun games
Play another online game such as WarRock or Crossfire
Hang out on MPGH, or go outside and chill with friends
Means you cannot connect, nothing is wrong with your computer. Its just simply patching .. and Nexon has blocked the client from connecting so no one can interrupt the patches.