System generates Shift/Alt/Control keypresses

OK. so this is strange.

I recently bought a HP Pavilion ab153nr laptop and installed Mate 15.04 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 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.


did you follow this advice when creating your boot media?:

I’m not sure how this could be relevant, but I used a USB stick rather than a DVD. I don’t recall it offering a burn speed option.


this is the part referring to a USB install:

"This does not appy to an ISO file being installed on a USB stick!!.

Attention!: Make sure you completely format the USB stick to FAT32 before commencing with Unetbootin or other USB installer software!."

Did you fully format the USB stick?. :smiley:

What on earth makes you think my install media could be relevant to this problem? The install process ran without incident, I updated everything with apt-get, and I started installing my programs

If you didn’t format the USB stick fully; there may well have been files from a different ISO on the stick which could cause a problem, simple as that. Not fully formatting a USB stick may well lead to input/output errors even if it looks like the system has installed correctly!.

I don’t know about the stick I used for the original install, but I assume so. Also, the problem has persisted when booting into live images on USB sticks where I did verify that there was a complete format. Booting into a live image of UbuntuMate showed the problem at a vastly reduced rate, but it was still present. Booting into a live image of UbuntuUnity shows the problem about three times per hour. And I booted into the Windows partition with a new keyboard monitoring program that shows a log of the keystrokes, and it again is not showing the issue, so it is linux specific

Interestingly, turning off the screensaver on my installed version vastly reduces the frequency of the issue. I have no idea why, though. I also changed the selected keyboard in the configuration to use the Microsoft Ergonomic keyboard driver, which didn’t resolve the problem, and a different generic driver, which I’ve had running for an hour now. I’ve had trouble burning an OpenSUSE stick that will actually boot, but if I can figure that out, that’s probably my next step.


take a look at the update guide and make sure your software sources download location is set to “Main server”, then try doing a full update again and see if that helps?: