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Since a couple of days ago I am experiencing a lot of freezes and I do not know how to investigate them.

It does not matter what I do - browsing, playing music, typing on LaTeX - at some point (after 2 minutes, 10 minutes or even after 1 hour) the computer freezes.
It becomes unresponsive to anything, the LED on the Caps Lock starts blinking and it stays like that forever.
Even the "magic" REISUB does not work (I enabled it to try to avoid corrupting my HDD with these frequent hard shutdowns).

The only thing that works is to long-press the power button and force shutdown.

I had a look at the log files in /var/log with no help (nothing gets registered).

This is my hardware.

I am on 15.04 with kernel 3.19.0-29-generic.
I tried to revert to old kernels with no help. In particular, 3.19.0-28-generic has the same problem.

Any hint on how to investigate this further?

PS: With Windows 8 there is no problem, even with intensive gameplay, so I would tend to exclude hardware problems.
PPS: temperatures also are not a problem, I was able to monitor them with sensors via a terminal.

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25
  • No comments? It is really an annoying behaviour :(
    – dadexix86
    Sep 15, 2015 at 6:11
  • try to exclude HW problem by Memory test. Memtest 86+ is available from GRUb loader.
    – Dee
    Sep 15, 2015 at 20:36
  • I didn't think about it, thanks for the hint. It's running right now, I'll keep you posted.
    – dadexix86
    Sep 15, 2015 at 20:42
  • what's your machine's manufacturer? blinking caps lock probably means something ("ask" the manufacturer, see for instance h20564.www2.hp.com/hpsc/doc/public/… ).
    – nutty about natty
    Sep 15, 2015 at 20:49
  • 3
    noleti implicitly pointed out that this is not related to manufacturer, but rather a feature implemented in the kernel: keyword now is kernel panic. PS: memtest won't "finish" (...)
    – nutty about natty
    Sep 15, 2015 at 21:09

3 Answers 3

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+125

The blinking caps lock is probably caused by a kernel panic, more info here. Look for log files as instructed here to debug this. It seems like there should be something related in /var/log/syslog.

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  • If it is a Kernel Panic, then probably to reinstall kernel would be a good solution. Remove all possible custom/proprietal hardware drivers before you do so.
    – Dee
    Sep 16, 2015 at 7:31
  • If it's a hard kernel panic, probably the only way to debug it is with a serial console help.ubuntu.com/community/SerialConsoleHowto (if you have a serial port) or hoping in a network console wiki.archlinux.org/index.php/Netconsole
    – Rmano
    Sep 16, 2015 at 13:20
  • @Rmano both options wuold be unavailable to me, since I only have one laptop and no other machine.
    – dadexix86
    Sep 16, 2015 at 13:40
  • @noleti Yesterday I modified /etc/rsyslog.d/50-default.conf following the instruvtions there (removed the dash). It happened right now again but nothing got registered in syslog. Something new showed up after reboot though, i.e. that Ubuntu has encountered an internal error and such, two times. These are screenshots (no copy-paste from that window, too bad).
    – dadexix86
    Sep 16, 2015 at 16:55
  • @dadexix86 Thanks for the screenshots. It definitely looks like a kernel issue ("oops"). Did this start recently? Maybe you can go back to an older version of the kernel. Not sure why no logging shows up.
    – noleti
    Sep 17, 2015 at 9:58
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Since the system became impossible to use, I reinstalled it.

After testing for a couple of says, it seems that the problem is solved.

Maybe I changed some configuration files in the previous setup that caused the error after some update.

In case the problem comes back I'll update this question.

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4
  • 250 rep lost forever... ;-)
    – Fabby
    Sep 20, 2015 at 21:35
  • 1
    I did not have any other real option ;)
    – dadexix86
    Sep 20, 2015 at 22:15
  • Sorry, but this is not how answers should be awarded. It is not about finding the easiest way out, but about identifying the root cause, and solving it. How is this answer going to benefit future users with the same problem?
    – noleti
    Sep 21, 2015 at 22:01
  • I'm sorry too, but this was the only solution. It will help future users in avoiding looking for something that does not exists for more than one week, risking breaking hardware with the frequent forced shutdown.
    – dadexix86
    Sep 22, 2015 at 5:48
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I had the same problem and it seems to be related to kernel 3.19.0-29. I am pretty sure about it because I began to experience it from sept.11 (the same date you reported), and that's the date the new kernel was installed in my PC. If I use kernel 3.19.0-28 it does not freeze anymore.

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4
  • To me it freezed also reverting to 3.19.0-28-generic...
    – dadexix86
    Sep 21, 2015 at 14:13
  • Here it freezes with 3.19.0-30, also
    – Angus73
    Sep 28, 2015 at 6:38
  • Then it might be worth opening a new question, maybe tou are luckier than me on investigating the problem via logs and serial console
    – dadexix86
    Sep 28, 2015 at 6:42
  • Thank you for the kind suggestion. New question is here askubuntu.com/questions/679212/…
    – Angus73
    Sep 28, 2015 at 7:47

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