My game will go dim and dark and I can't open any menus at all. Anyone else have this happen? I have to do an end task and restart the game.

You should verify the game files, or update your graphic driver.

You're playing a mod and invoking the in-game console by pressing ~ (US keyboard, in any case the key below ESC).
Press ~ again to dismiss the console.

That key is - by convention - the key to call up the in-game console if the game has one, and the optical effect of dimming the graphics is also quite common.