Dell Latitude D630, Screen goes white at boot

Hello Everyone,

I 've been using my dell latitude D630 for 2 and a half years now, it has not given me any major problems since the past 2 months..

2 months back, the screen of my LCD started showing in diferent colors, the text would be here and there.. the screen would be divided in 2, and there would be straight lines with gaps... I would either restart it, or just turn it off for sometime and then it would start normally.. Then, the problem became frequent and i thought of downloading and installing the latest drivers of my nvidia quadro NVS 135M, after installing the latest drivers the problem still continued, so i uninstalled it, and installed the actual drivers i got with the laptop.. This solved the problem for 2-3 weeks, and then again the same problem started, i would also get the Blue screen of Death with error NV4_disp... i would restart by going into setup and sometimes changing to boot from onboard video card and it would work.. BUt 2 days back, i got the blue screen of death error, i restarted the laptop and all i saw was a bright white light, although it seemed that the laptop's other devices were working.. I connected an external monitor and it showed everything properly.. Suspecting loose connection of display wire, i opened up the lcd and tightned the connections... But still the WHite screen continues.. 

Please suggest a solution, or a way to get closer to the real problem.. I am into IT and laptop is everything to me... Appreciate any help..

thanks