I'm not entirely sure what could be crashing it.. I'd go over what was recently done and go through recent files placed and remove and replace and all that to see what could be causing it, which would be a process.
I'd personally suggest, re-downloading another FH if you cannot find your issue, and move things over, move the map files over, presets, anything you don't wanna lose and such, do it piece by piece and test the game as you do so to see if one of the things you place in causes it to crash. Best way to find the issue at hand. Kinda complicated I know, but it's always good to give it a shot if you can't figure it out. Just have to remember to restart after moving each "section" of things over. (: Could be an object, or anything.
Just my personal way of fixing issues when i have issues like this! Guud way to find the problem and prevent it happening again. Wish ya luck, let me know if you decide to give it a go and if it helps at all!