The screen on my 20-month old Sony laptop (dual-Onyx black LCD) suddenly lost all its brightness to the point that almost nothing is now vsible! An external CRT display connected to the laptop works Ok. Tried to increase the brightness using the keyboard but it is already at maximum (reducing it has no effect either!). It would see to me that the graphics card (NVIDIA GeForce FX Go5600) is as everything is displayed fine on the external monitor and there are no other problems using the laptop. Please help.