crashes after a while into the game

i was a big fan of the original civilization.
this game is very nice, bringing the old version into the modern day with better graphics and a more complex scheme.

however, a big flaw is that ive never been able to finish the game. i can get fairly far into it, but at a certain point it just crashes.
this is on a mac os x 10.6.8.
my guess is that its leaking variables somewhere.

so it keeps me entertained for several hours, but i never have the satisfaction of finishing the game.

bob vander snoot about Civilization IV