There really is no way to tell if the file is still opened other than attempt to open it in your program. If open fails, wait a little bit then try again. stay in that loop until open succeeds or some timeout value expires.
First, sorry for my bad english. I'm from Ecuador and I speak spanish.
Now, open notepad or notepad++ and write the configuration that you need, then save as NSC.ini in the desktop of your PC, then copy and replace the file in C:/File Programs/NSCliente ++ directory
and is solved...