E1505 Dell Laptop Black screen Windows start

Hello,

I am working on a project laptop. thinking the problem may be software related I fdisked the master boot record and formatted the whole hard drive before doing a clean installed of Win XP sp3. I can still have a screen by using the vga out and hooking up a monitor. The screen on the laptop works for a minute or two every boot, but has to be transferred to the monitor before actually using it

screen looks ok before going black. video cable suspect. any suggestions?