Happyme idk if thats a ban if you really want to know if your banned change your ip and try to login if it still shows that message then you should try to reinstall the game. Or you could got to the combat arms site and search your combat arms profile and if it shows that you have a high rank but everything is at 0 then you know your banned well have fun hope this doesn't happen to me :P
Maybe it has something to do with the C:\Documents and Settings\All Users\Application Data\NexonUS dir.
There could some data there that represents some form of a unique id.
Id suggest making a new windows user name, then reinstall it to a different directory.
I know its worked for me a few times in the past with various software.
But if your actual account is banned on the server side i think you just might have to create a new nexon acc.
Hmm well thats weird i would think it would show your ip is banned error or something it might be a good idea just to do what the error says go to nexon site and post on the forums and see if anyone gots a suggestion. Maybe a admin can help you out. Also if you get it working let us know also if you don't get it working you have been banned please tell us what hacks you used so we don't end up in your position thanks bro i hope you aren't banned!
Tried deleting NexonUS folder which rendered my install broken so I reinstalled and the installer created a file called NGM.log on my desktop which it copied to the new folder. I tried changing the "Game Code" in the NexonUS folder which didn't make a difference.
On the bright side, this is happening to other people.