I have an annoying problem where my desktop suddenly becomes unresponsive to my mouse. This always happens randomly, at random times. Sometimes I can work for hours with no problems, sometimes this will happen 1-2 times within an hour.

The unresponsiveness comes gradually. First I can only control the window which was last focused. I can move it, click inside on UI elements, scroll with scroll wheel etc. Then when I start to click on other windows or the task bar, things start to get worse. I seem to be able to bring windows to front and use them, but I cannot move or re-size them anymore. Then I cannot bring any windows to front anymore with my mouse, neither by clicking on them nor through the task bar. And finally, clicking inside the window on UI element stops working. Instead the clicks seem to go through to the desktop, because I can open programs by clicking on locations where I know I have an icon on my desktop.

Only my keyboard keeps working. I can alt+tab through windows and close them with alt+f4. I can also control the windows with my keyboard, like tabbing through UI elements, entering fields etc.

My current workaround is to open a terminal through the app launcher (alt+f2) and then:

sudo systemctl restart sddm (Update: switching to a tty with ctrl+alt+f1 and then back to the x session with ctrl+alt+f7 solves the problem, I get back mouse control. So that's an at least less annoying workaround.)

Then I can log back in and everything is back to normal.

Right now I'm using the Kubuntu 15.04 Beta 2, but the weirdest thing is that this problem isn't related to a distribution, or desktop environment. I installed Kubuntu yesterday, because it finally happened to me yesterday that my Arch Linux installation broke by doing a system update. I was unable to fix it so I decided to give Kubuntu a try.

On Arch I've been using Xfce4, and there I had exactly the same problem! So I guess this problem must be related to my hardware somehow (never had any problems with Windows on this machine by the way).

My system: CPU: Intel Core i5-3459 GPU: ATI Radeon HD5850

On Arch I was using the open xorg ati drivers. On Kubuntu though the xorg drivers gave me very poor performance, so I installed the proprietary fglrx drivers, which made everything run smooth.

Kubuntu (and previously Arch) is installed on a Sandisk 64GB USB 3.0 pendrive (not live!). I did this because I didn't want to mess with my Windows installation, and I never had any problems other than those annoying freezes.

On Kubuntu the .xsession-errors log gets filled with every click I make on a window. Unfortunately only now have I noticed that I forgot to back it up before restarting my X session, but I will attach some errors as soon as this happens again (shouldn't take too long, unfortunately). Anyway, when I inspected the log it didn't show up anything obvious. I tried to google for some of the log entries but nothing useful came up. dmesg and X.org.0.log also don't contain any obvious errors.

Other than the .xsessions-errors log file, how would I go about to debug such problem?

This question basically describes the exact same problem I have: https://askubuntu.com/questions/56645/ui-elements-become-completely-unresponsive

But unfortunately none of the answers did help me.

  • May be fault of an application taking control over the mouse and not yielding it later? That's something that has happened to me several times with Spotify on Linux, having to go to the tty and back to recover my mouse. – Alicia Mar 28 '15 at 22:52
  • Going to tty and back helped me when I was using Arch. But on Kubuntu I get a blank screen with strg+alt+fn, but that's another problem... and right now I have nothing fancy installed, expect Chromium and the default Kubuntu packages. I've been only playing around with the KDE apps so far. It must be somehow hardware related but I just can't figure it out. I have a Madcatz keyboard and a Logitech G35 USB headset, they work fine but may external devices like these cause weird behaviour? – Simon Mar 28 '15 at 22:58
  • I just realized that on Kubuntu, ctrl+alt+f7 brings me back to my x session! I always though it's f1, like it was on Arch :) Now that's at least a more convenient workaround than killing the session. After switching I get mouse control back. – Simon Mar 28 '15 at 23:25

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