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Not able to save game .Here is the solution.
You can create an offline profile for which you need not register.
"Skip login" in Rockstar social club.
Then go to "Games for Windows Live account" by pressing the "Home" key on your keyboard.(Its near page up/down buttons on a desktop keyboard)
Click on "create offline profile" or something like that. Don't know the exact words but you'll find this offline profile option easily. Then you may save your game by sleeping in your safe-house.