K. Uninstall it. Now - with WinRar, there should be a place called "Extract To" actually a button. CLick it and then send it to C:\Nexon\Combat Arms.
Now, edit settings.ini. REMEMBER NOT TO PUT A SPACE BETWEEN UR USERNAME AND PASSWORD:
CORRECT WAY:
username=carbon
password=123
WRONG WAY:
username= carbon
password= 123