It is really simple to disable the Internet access on the system. There is a little slider bar that turns Internet access on or off. The slider bar labeled Wireless is located just to the right of the A button on the right side of the 3DS system. A yellow LED notifies if the WiFi is enabled. If the light is on, disable the WiFi by sliding the wireless button down and releasing it. When the light goes off, the WiFi has been turned off.
This should resolve any conflicts and prevent the game from freezing up.