I've got an issue where whenever I go to the Castle, either by fast travelling or walking there my game crashes to the desktop. I'm not running any mods and have updated my drivers but still no resolution. One interesting note is that if I look at the settlement details in the pipboy data screen it shows as 0 beds at the site. Can anyone assist or know of a similar issue?

I had been using Sanctuary as my main settlement and after a certain point, I would get CTDs on fast travel to or right near it. I ended up having to start a new game as I didn't find any help about it. My suggestion is that if no one comes up with a working solution, on your next play through, leave some empty space in your settlement budget. May have nothing to do with it but I've "Optimized," my settlements this run and haven't had it happen yet (knock on wood.) Best of luck and hope someone can actually help you out. Cheers!

Does this happen on a previous save or new game? Can you upload the save somewhere so others can try it?

Use http://tinyupload.com/or something similar.