When I first started MM9, my computer was exactly at the minimum specs, and I experienced this very problem from time to time and iirc it got worse the further into the game I played, just as described by Bones. I increased the amount of RAM from 64kb to 128 which is normally not much of a cost (it was in my case, but nevermind that ). Loadingtimes were not much affected, but, as far as I can remember, I have never had the game crash during loading since that.

Now, DO note that technical problems are usually way above me, so unless a more competent person supports this, spending money on RAM just because it seemingly helped me, might be dangerous, heh....