Latitude E7440 black screen after undock

Same issue here, disconnecting a beamer leads to a black screen once every two or three times.Even changing screen resolution sometimes has this effect.

Which means I'm afraid to go to customer / prospect presenting something.

Which leads to the conclusion: if not fixed quickly, returned.

How can you tell if you have the newest Video driver?

I had the same issue and the video driver number is the same (10.18.10.3574) the dell site has a A12 at the end.  After I run the install and restart and check the version it still has the same version number and same date for the driver (4/24/2014).

So is there anyway to tell you have the A12 Jan 15th version of the driver?

I installed A12 driver as well, seems to be same driver version when looking in Windows 7.

This is big issue for me, I can't present  smoothly when visiting clients.

Right when i plug in projector or boardroom TV into video port my screen goes black.

I cant toggle between between "extend" or "projector only" as screen is black.

If I unplug external monitor cable, I still cant get my display back on my laptop.

Only solution is hard reboot, which does not look good when you only have so much time in front of customer.

Any other ideas?  thanks!

Try the following:

Windows Key + R> type "powercfg.cpl"> Choose what closing the lid does>When I close the lid: Do nothing (select this option for both on battery and plugged in)> Save Changes

Or navigate to the control panel via the start menu>Hardware and Sound>Power Options> Choose what closing the lid does>When I close the lid: Do nothing (select this option for both on battery and plugged in)> Save Changes

Elwardo, I've been researching this problem as I have a couple of E7440s that are doing it randomly. We've found that people having problems are wearing wristwatches that use a magnetic clasp, and the magnet triggers the "Lid closed" switch inside the laptop. That makes the machine go black, although it's not consistently going to sleep, because the magnet is often moved away quickly so it 'wakes back up' but the screen stays black.

Just curious if you wear a watch with a magnetic clasp. I figured this out when I had E7440s stacked on top of each other in my office and moving them would put them to sleep (or wake them up). I though I was bending something. Started researching more and found magnets are in the lid and a magnetic switch is in the case to tell the bios if the lid is open or closed.

I have changed power option, so it never goes to sleep and updated BIOS.

Will test soon, when i have access to projector or large boardroom TV.

I do wear a Samsung gear fit watch, not much metal on it, but it is an electronic.

Thanks for the tips, really appreciate it!

same issue but with unplugging HDMI - laptop screen and HDMI are on, remove HDMI laptop screen goes black

same issue here, still.

tried with multiple different video driver versions (incl the latest), and yet experiencing the issue. not always, but very often.

usually screen is blank after undocking; or sometimes ok after undock, and then blank after (going to and then) resume from hibernation. it is super annoying.

DELL - please, is there a solution??

(win7 x64; When I close the lid: Do nothing; power settings reset multiple times)