black screen problem

i have a dell laptop inspiron 8600c 15"4 screen, bought in 04/01/2005, with an ATI radeon turbo 9600 graphic card, centrino 1,7 processor, 1 gb ram.
suddenly the screen turned black i thought it went to standy mode,but it wasnt ... i restarted the pc to discover that it still black, but it's not really black because if i look closely with some light i can see that the pc work normally. i tried to connect it to normal screen, the pc worked normally.
i want to add that since few time, the color was becoming a bit red, but i thought it's not a big deal and i don't know if it's related to my last problem.
The only problem also i got 2 months ago, was that the laptop was going suddenly to standby mode, i cleaned it with spray and i launched the dell diagnostic tools, the problem was solved.

i looked in the net they say it could come from motherboard or inverter or a third thing called LCD backlight...can anyone tell me from what comes my problem ? or how can i know from which of these 3 reasons it's coming ?

thanks in advance for your help.