The arrow keys navigation does not work in Excel application on your system. The same arrow keys navigation just works fine in other applications.
You probably have the Scroll Lock special key pressed/enabled on your keyboard which causes this behaviour. To fix click on Scroll Lock special key to release/unlock/disable it. The Scroll Lock special key varies from keyboard to keyboard. On my system keyboard, the Scroll Lock function is associate with Home button. To control it, I need to press Function key (Fn) + Home button.