02-09-2014 03:28 PM
I have a ThinkPad Twist running Windows 8 driving a single external display through a Lenovo USB3 dock. When I extend my screen across both displays or if I close the laptop and just use the external display, then the display periodically goes black and then recovers. If I duplicate the laptop screen onto the external monitor all is good.
Sometimes this is caused by UAC and other password requests. In that case the screen stays black until I respond to the pop-up on the laptop screen. I understand that this is a security feature. Other times it seems to happen spontaneously. Several times I have sat and watched the external display go black for a few seconds then recover several times a minute without any user activity. I don't think that's related to a security feature.
I also have a Lenovo X1 Carbon running Windows 8. When using it with the same USB3 dock I have never experienced this issue.