.CFG In Vista...

Why can;t I save a .cfg file in Vista. I open it and then once I have edited go to save and it says cannot find file path please specify or whatever and I do. Then it says can't find file path and that's it....
If this goes unsolved, it will mean no more repaints
:-/
Thanks in advance
If this goes unsolved, it will mean no more repaints

Thanks in advance