The crashes probably don't have anything to do with your hardware.  There's just more stuff going on later in the game that could cause a crash to occur.  I've been having a lot of crashes later on in games as well.  There's probably nothing you can do.  If you reload your autosave and it crashes again at the same spot again and again, you can submit your save game, and Stardock will probably be able to fix the problem in the code causing that particular crash.  Any game as ambitious as this one is just going to be riddled with bugs.