Managing two frames

What I am trying to do is have one frame open up - if a config file is
not present, ask some config related questions then open the main
window.

What is the best way to do it.

I keep trying to do another frame from within the first one but it
always crashes.

Or would it be easier if I need the config file - to set the window to
get it and then redefine the windows to match the new parameters.