I can't say I understand what's going with your game, but there're only two things I can think of that would make your screen go black:
1. The ENB comes with a Colour-Palette and you have it accidentally deactivated. Check in the enbseries.ini for "UsePaletteTexture=true".
2. Something has messed with your Renderer-Settings. Make a backup of the Fallout-folder in the user/My Games folder. And then delete or rename both .ini-files and the RendererInfo.txt.