Both Screens Go Dark When Cable Plugged In

[Silkworm]

Hello, I'm fairly new to Kubuntu, but I've been running 15.10 on an ASUS X551M for while now, and using a VGA cable to connect to a second monitor, and it has been working very well.

A few days ago, it began behaving erratically though:

When I plug the VGA cable in, my laptop screen goes black.
I can see my cursor on the second monitor, but it can move only up and down against the left edge of the monitor. The rest of it is black as well.

Restarting the computer does not solve it.
I also entered into Display Configuration and clicked Reset and Defaults, but this has not worked either.

After I unplug the cable, the laptop screen comes back on, and I often get messages that krunner and/or Plasma have crashed. The taskbar disappears and re-loads, and the position of previously-open windows hops around.

I would be grateful for any advice--thank you very much!

[Teunis]

I can't help you much, I do notice the present version of Kubuntu has a rather fragile way of dealing with video, especially multiple monitors.

It is important to keep your system up to date with the latest packages and they might fix issues that were introduced a few days earlier.


One simple thing you can test is to boot with both screens already attached.

oshunluvr posted this idea that might work in your situation:
https://www.kubuntuforums.net/showth...l=1#post383941

[Silkworm]

Thank you very much. I think your hunch that I needed to get the system up to date was probably correct. When booting with both screens attached did not work, I went ahead and reinstalled 15.10, and that solved the problem: both screens work again--even though Plasma still sometimes crashes when attaching or detaching the VGA cable.

[Teunis]

Just about the same here, it works and looks great but fiddling with the second screen can cause Plasma to go down.
Luckily a few seconds later it comes up again.

[sithlord48]

it seams at least for me that krunner tends to crash apon its first use sometimes. i think when you plugin another monitor krunner is triggered to run kscreen detection for the new monitor and it seams w/ krunner failing not running the command and in that case takes plasma with it .

[LinkBot]

Bug 357085 - Unplug VGA output then plug again and plasmashell segfaults : https://bugs.kde.org/show_bug.cgi?id=357085

Bug 359234 - Plasma crasch when disabling and enabling laptop monitor when two external monitors are connected : https://bugs.kde.org/show_bug.cgi?id=359234