It sounds like a bad news as this could be an indication of a screen failure. If you can plug in an external monitor and the display is good then I`m afraid it would confirm my fears.
The only other cause that I have come across (on a desktop not laptop) is memory corruption - sometimes caused by bad contacts in RAM sticks or the graphics card. This can be cured by re-seating the RAM and/or card(s) or even by powering down and re-booting. You could try removing the battery from the laptop (make certain it is turned off first) and leave it for a few minutes then refit it and see what happens when you boot up.