You are getting this error because the file you are trying to run is trying to access the computers memory. Because you are not running the file on a DOS or Win 3.X machine, NTVDM will not allow this. NTVDM allows a 16-bit DOS program to execute on Windows. It is basically a DOS emulator.
when you get this message at window startup or during runing of some program
when you get this message at window startup or during runing of some program