Are you shutting down all non-essential programs (especially anti-virus) before starting the game, and do you do so before re-installing it?
Do you have other games currently installed? Bad memory could account for random crashes, as well as consistent crashes that can re-installing multiple time could fix (ie random corruption during install). In that case problems should also occur in other games or memory intensive programs (burning DVDs, video editing, etc).
There are a couple memory testing programs you can try:
Memtest86 /
MS Windows Memory Diagnostic.