I did that, everything checked out fine. I tried the game again after that and upping the graphics through launcher and it seems like some of what I've done / what has happened since, if anything, has fixed my issue. I had to play the starting area through again but once I reached the door, it worked fine that time and everything else seems in order too now.
If it was the graphics changes I made, then this is definitely the first time making a game harder to run has fixed a crash issue for me, but since there was nothing else...
Still, though, I'll be paranoidly saving and exiting in front of every door as long as I'm not being chased by anything ugly from here on out for a while