La Boîte à Pain - Le forum

Black marks on the computer screen could appear due to damage, pressure on the screen, pixel burn-in or backlighting issues. Firstly, use a microfiber cloth to clean the screen from dust and any marks. Do not put any pressure on the screen during cleaning since the pressure would worsen the problem. Reboot your computer and see if the marks are still visible. You can update the graphics card drivers or plug in an external monitor to check how the display looks. In case the black stains remain in one place or expand over time, the LCD screen is likely damaged and needs repair by a professional technician.