what do I rename the file
Sorry that you're having troubles... Obviously you tried the "perma-fix" and refresh method, so let me offer a different solution:
Just before entering the zoned area of troubles, spam the enter key until you get to the caves. You'll know what the caves are when ya see em.
Save the game once you're in the caves, and reload the game (closing the game may be a requirement). It fixes it on a "temporary" scale until the devs get it fixed.