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OK, so this is strange.

I recently bought a HP Pavilion ab153nr laptop and installed UbuntuMate 15.10 on it. While setting everything up, I noticed that the screensaver would occasionally stop showing (ie, go back to the desktop) without me touching the computer, but I didn't worry about it. When I started using the computer, however, I noticed some additional strange behavior. Scrolling in my browser would sometimes cause the page to zoom in or out, and while typing in my IDE I would get apparently random commands.

Running xev shows that something is sending Alt_L, Control_L and Shift_R events. I ran xev overnight, and it counted 5 Shift_R KeyRelease events, 15 Alt_L events, and 25 Control_L events. Interestingly, there are no KeyPress events, though there are FocusOut, FocusIn, and KeymapNotify events. I don't know enough to know if those are relevant, however.

It's not related to my KVM switch (symptoms persisted when I disconnected it) or the laptop hardware (booting into the Windows 10 partition and leaving either the screen saver or the on-screen keyboard up for hours showed no unexpected behavior.)

Anyone have any ideas about what could be causing this? A way to better identify what process is sending these events? The laptop is supposed to be my development machine, but it's pretty much unusable with random control characters being sent every 10 minutes or so. I've put the log at http://pastebin.com/3inwfuxG if anyone wants to take a look; everything after the Scroll_Lock presses until the mouse movements at the end of the file is from when the box was left idle over night.

UPDATE 10/06: I rebooted into a Ubuntu/Mate Live stick and the problem persisted,but at a vastly reduced rate; maybe a few times a day instead of a few times an hour. I tried an Ubuntu/Unity 15.04 Live Stick, and I saw the problem ~3 times per hour. I went back to my installed system and deleted the two keyboard shortcuts I'd added, but that didn't change anything. I'm not using any keyboard remapper unless one comes enabled by default in Mate. But the comments about the focus changing got me thinking, and I watched when those occurred. It's hard to tell since the log doesn't timestamp them, but those are related to the screensaver coming on and off. The focus out happens when the screensaver starts, then there's an unpredictable length of time until the random keyboard event, and then the focus in occurs as the desktop comes back. I turned off the screensaver to confirm this and get a cleaner log, and two (or maybe three) very strange things happened: I started getting keyPress events for the mysterious keypresses; the rate of keypresses dropped significantly, down to what I saw on the Ubuntu/Mate Live Stick; and I've only seen Control_L events since then, and not Alt_L or Shift_R, though given the sharply reduced rate of occurrence, it's possible that's just a coincidence.

So on the installed system with screensaver enabled, I see multiple events per hour. On the Mate LiveStick with screensaver enabled, I see a handful of events per day. On the Unity LiveStick, which doesn't even have a screensaver, I see a smaller number of events per hour. And on the installed system with screensaver disabled, I see only a handful of events per day. There's no consistency here, so I'm missing something.

This is driving me batty. I was almost ready to call it a hardware problem despite the evidence until changing settings on the box changed the rate of incidence. I still might use cygwin to put xev on the Windows partition and leave that running overnight to see if it captures anything.

  • Do you have the same problem with another account? With a different desktop environment? – Gilles Oct 2 '15 at 22:02
  • I haven't tried another account on the machine. I did boot into the liveCD image of 15.04, and have left it running all day; the issue has only occurred twice that I've noticed in over 12 hours, so I'm thinking maybe a driver update after install? Tomorrow I'll try another account and/or another distro with a different desktop. – jbhelfrich Oct 3 '15 at 6:27
  • A bad keyboard driver could inject spurious keyboard events, but not focus changes, and keyboard drivers haven't changed in the last decade or so, so I don't think it's that. What I'd go looking for is some kind of GUI customization application, maybe a keyboard remapper or a macro player or something. I don't know how to identify it; trying with other different GUI sessions setup that may or may not include that buggy application would be a start. – Gilles Oct 3 '15 at 11:25
  • See update above – jbhelfrich Oct 6 '15 at 15:10
  • We are in the exact same issue. We found this bug report: bugs.launchpad.net/ubuntu/+source/linux/+bug/1532746 Did you find any solution? – EnricoGiampieri Mar 21 '16 at 16:51
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I had the same problem and guess you have a intermittent stuck keyboard. Someone probably spilled something on it. On mine it affected the keyboard and mouse.

Not sure this will work, but if you can remove the keyboard and connect a USB keyboard, you might be able to test that theory.

  • The laptop is less than a month old. It has been on my desk the entire time. No one has touched it but me. There are no fluids on the keyboard. It is raised above the surface of my desk so it couldn't easily be spilled on. My wife would tell me if she did it, my kid couldn't clean it up well enough to hide it, and the cats wouldn't clean up at all. One of the affected keys is on the opposite side of the keyboard from the other two, and none of them are adjacent. And, as mentioned in the original post, when booted into the windows partition, the behavior does not occur. So, not hardware – jbhelfrich Oct 2 '15 at 5:35
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A workaround has been identified for this issue. In the GRUB config, specify the kernel parameter 'i8042.dumbkbd'. This will disable some or all of the keyboard lights, but will prevent the symptoms described.

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