I had the exact same problem with my 3ds if fixed it by: 1. Taking off my screen protector. 2. Wiping the screen with a lint free cloth. 3. Gently brushing the edges of the screen with a toothbrush. 4. Using a hard, plastic card on the edges of the screen. 5. Booting into calibration mode (pressing L+R+X while turning on). Hope this helps!