Question : Problem: Laptop monitor does not come up, but comes up on external monitor only

We have a Dell Latitude D531.  I can hook it up to an external monitor and it's fine (the external is identified as 1), but there's nothing on the laptop screen.  I've checked the settings and as far as the Dell knows, everything's cool (shows one monitor).  The laptop is usually docked, but this problem happened when it was undocked...but this hasn't happend before.  Monitor settings aren't rocket science, so I 'm hoping I'm missing something quite obvious.  Any ideas?

Thanks!
Kevin

Answer : Problem: Laptop monitor does not come up, but comes up on external monitor only

With the external showing there is the possibility of having an issue with the LCD display.
It can range from
-Simple keyboard hotkey combination Fn + f8 used to switch from external to internal video screen(not likely unless there could be some profile settings expecting an external screen at all times)
-a dead inverter which powers the CCFL bulbs in the screen. Remove external monitor, can you see a faint image of the desktop when a flashlight is shining on it at an angle. I usually look for the START button in the lower left or the clock in the lower right corner of the screen.
-Loosened video cable on the motherboard to the LCD screen. This wold require some disassembly , usualy keyboard removal to reseat the cable. http://support.dell.com/support/edocs/systems/latd531/en/sm/display.htm#wp1057591
-Bad LCD screen, if all of the above do not work.