On some computer systems, The Sims 2 displays Ground Cover textures - both custom content and The Sims 2 content - over a larger area (20x20 tiles) than normal (4x4). This is known behavior with the nVIDIA GeForce 2 family of video cards, nVIDIA GeForce4 MX, and nVIDIA GeForce4 4400.
Question and answer provided by the
official FAQ.