I need to know :/ to fix my CTD when i try to save.

Right click falloutnv.exe choose properties / previous versions / restore.

You shouldnt have to uninstall the patch. Steam may just try to reacquire the update anyway. I dont believe you can use previous versions unless you make a restore point.

Or you copied the old exe files before the new patchs arrives. I have every version of the files to date backed up on a backup drive. You need to put Steam in offline mode to use them or it will update them again.

Not that I have needed to go back, it's nice to know I can if need be.