Blade_Runner4000: The same happened to me. :(
I regret to inform you that the only solution I found was to revert to an earlier save and resume playing again, trying to do things in a different order, praying that it wouldn't happen again.
As to why it happens, I'm not sure, but it seems to be related to what the game expects you to be doing / have done at a certain time, and if you screw that up, BHAM you cannot save anymore (nor exit the game, because it tries to autosave then crashes)
I experienced it 2 or 3 times in a single playthrough, at different points, and saving often (instead of relying on autosave) is what got me through.
By the way, resuming the last autosave before you crashed DOESN'T fix the problem. It will only crash again because you're already past the "screwing point". For me, I HAD to go back to an earlier -if not much earlier- manual savegame.
Not much but it's what I got. Hope it helps :)
I actually "fixed" it by loading my save game from the list, rather than just clicking "resume from last save". I don't know why that fixed the problem, but it did.