Problem opening korean warrock after closing

Ok i'll be playing korean warrock and when i am done i close it and go do something else but when i want to go back on it i get a gameguard error saying "game has being repeated run or gameguard is still running quit the game and rerun" So i click ok and the client closes so i try opening it again and i get the same message and to play korean warrock again i have to reset my pc which is quite annoying, any suggestions?

restart pc and you can play again, i only get this, if i exit over task manager, if you exit normal, i get no problems... restart pc and it works...