When selecting "load game" during gameplay, the game is allocating more memory every time it performs the load function. This continues until all available system memory is used, at which point the game becomes unresponsive to the Quit command. Follow the steps below to reproduce.
Start Windows Resource Monitor. Start the game and continue or load a save. Alt+Tab out and check how much memory the game is using. Go back to the game and press Escape, select Load, and load a save. Repeat this process over and over and each time you do so, you'll see the game has allocated more and more system memory.