Latitude D630 monitor not working on some boots

I've had a D630 for a little under a year now, and ever since I re-formatted about 6months ago, I would have this problem where everything boots up just fine, but nothing shows up on the monitor. The lcd's backlight is always on and I know everything else is fine because I can properly shutdown by hitting the power button and U.

This doesn't happen every time and is actually pretty rare now. All I know is that the problem started right after I formatted and re-installed XP. And whenever it does happen, it takes 5 or so reboots to get the screen to work again. I should also mention that I normally use an external monitor with the laptop's screen off. That would be my best guess as to why I'm having this problem.

Can anybody help me out? I'm tired of crossing my fingers every time i turn on my laptop.

 

I think it could be wrong function of FN function with pres FN+"CRT/LCD" button, if not, i am not pretty sure, but I try to explore Bios about it, my D620 working properly standalone or with docking station. But I have problem to work with 3 monitors in same time, but I think is not possible, becouse RAMDAC od Graphic card support only two outputs in one time, doesnt matter that you have 3 display conected in one time. Buil LCD, LCD on DVI-D, CRT on RGB port for example. Try to write which type graphic do you have and if could see the boot sequence or just only windows after login disapear. It could be more reason, i really apologize, it is my first post and my english is pretty bad, becouse I am from Central Europe ( now living in Barbados, Caribbean). Respect for comunity and I hope that I could be part of general knowledge..