BatMan Arkham City stop working, plz help.

Hi to all seven forums.
today I install Batman arkham city, and its works fine, I play it half an hour, then I quit it and do some other stuff, then later I launch the game 3 to 4 time and its working perfect.
few hours later I launch it again, Nvidia logo, creator logo passes and windows live profile sign in normally, and then I click on last save to resume it a black screen appear and a little while windows message appear that Batman arkham city stop working, close this program, when I close it this message appears, maybe someone know this error message, so I m requesting to help me.
if it is the save problem, then why its not crashes on first 3 to 4 time launching,,?

sorry for bother guys, I realize the only "Park Now" save corrupted every time, so I clear this area to avoid hanging again, next save point is ok.
solve.