Before trying to help me, if you have not infiltrated the Institute this will contain

SPOILERS

During the battle for bunker hill, once I have fought my way to the synths in the basemant and am deciding how to handle them. No matter how I end this quest, no matter how or in what order they are handled as soon as that objective clears I get an immediate crash to desktop.

I can still leave the area and quest around to my hearts content, but no matter what I do that quest cannot be completed.

I have updated all my drivers, tried changing around graphics settings, and even disabling all of my background programs. No difference whatsoever.

Specs~

Intel i5-3570

Nvidia GTX 970 (4GB)

6GB DDR3

Yes I realize I am technically under minimum ram, but unless something psychotically heavy happens when you finish that quest I have had no problems running it on 6GB from day one.

EDIT - The crash is straight to desktop, no error messages etc.