I have the same problem with far cry v1.4 downloaded from gamestop. The game will lock and the critical exception error will come up at auto savepoints in the game. I thought I had solved the problem by running it in windowed mode verses full screen, as one had suggested. One other workaround I've found is to avoid certain savepoints by taking a different route through the map - sometimes this isn't feasible of course. When the game locks and the editor comes up, I can click save document and it will say it saved the checkpoint but didn't really - after aborting to get out and going back in, there is no new savepoint in the campaign screen.
Some savepoints work fine. I've not found a pattern to the issue. If any one has any ideas for this, please let me know. My PC is very new and I have the newest directx drivers, and am running the 1.4 patch. What else is there?