I received an unreadable disc error while playing the downloaded version of Bioshock. The game crashed prior to reaching Point Prometheus (near the end of the game), and thus losing my latest save as well. I have cleared my system cache and am re-downloading the game. Is this a common issue? I would like to know before I risk attempting to get back to that point only to have it crash again, and having wasted my time on an unplayable version of this 5 1/2 year old game.