In the movie WALL-E all humans have left Earth aboard a massive space ship because Earth has basically been turned into a giant unlivable trash pile. When WALL-E and his friend EVE discover a small plant growing on earth they bring it to the massive space ship to essentially show the humans it is time to return to Earth. However, when the computer finds out EVE possesses the plant, it decides to try and destroy the plant.
Basically I am wondering why? Why does the computer decide to seemingly break its programming and fight the captain?