Ok, that's a bit bad explained, but I just started the game and don't remember all names yet, sorry xD.

So, I got to the first village of the game, talked with some natives, and got lost while trying to find the temple where the magic stone #52456 is hidden.
I talked to the guy who takes care of the ostrich-like riding animals, purchased one, explore a bit and went back, because he needed me to kill some animals. I did it, went back and the game crashed. It seems a message appeared, but I couldn't saw the message and have to reset the computer.

I have installed the awesome hi-res patch, but I don't really know if it has some relation with the crash, so... any suggestions besides try again the mission on 640*480?

EDIT: Repeated the mission and everything went ok. Saved the game, kept playing and a random crash occured. Seems to be patch instability :S

Happens to me too with the high res patch, it also crashes often after dying.
Also try not to run too many other programs in the background.

Positive side is you learn to save more often :P