I've found a number of posts on related problem to mine, but none of them seem to address the exact issue. My apologies if I missed something and this ends up being a double post!
Basically, for a few weeks now my laptop erratically shuts down when running Ubuntu 12.04. What happens is that it displays the shutdown dialogue:
Shut down this system now? You are currently logged in as .... The system will automatically be shut down in 60 seconds. OK / Cancel / ...
Regardless of what I do at this stage (press one of the buttons / do nothing), the computer will shortly after completely shut down. I mean shut down in the brutal fashion, as in turn itself off immediately with all software complaining after the next boot that they weren't shutdown correctly.
I am running Windows in dual-boot and don't experience the same problem there. Maybe this doesn't completely rule out a hardware issue but it seems to make it a lot less likely. As most posts on similar issues talked about heating, I also installed sensors to monitor the temperature of my laptop (a Toshiba A660-18N). The HD is at around 30°C, the graphics card and CPUs fluctuate between 56°C and 62°C, so nothing out of the ordinary from what I understand.
I looked in various log files for some hints as to what's going on, but didn't make progress. Below is an excerpt from the last time this happened. The laptop died at around 12:08:00 and I rebooted shortly after. The messages from 12:08:45 are from startup already.
Feb 4 12:06:34 splinter kernel: [ 1504.401787] type=1400 audit(1391515594.358:36): apparmor="DENIED" operation="open" parent=1 profile="/usr/bin/evince" name="/shared/Files/dphil/thesis/0_acknowledgements.aux" pid=4562 comm="pool" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000 Feb 4 12:06:49 splinter kernel: [ 1519.750029] audit_printk_skb: 168 callbacks suppressed Feb 4 12:06:49 splinter kernel: [ 1519.750033] type=1400 audit(1391515609.706:93): apparmor="DENIED" operation="open" parent=1 profile="/usr/bin/evince" name="/shared/Files/._Lbfgsb.3.0" pid=4579 comm="pool" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000 Feb 4 12:08:45 splinter kernel: imklog 5.8.6, log source = /proc/kmsg started. Feb 4 12:08:45 splinter rsyslogd: [origin software="rsyslogd" swVersion="5.8.6" x-pid="1046" x-info="http://www.rsyslog.com"] start Feb 4 12:08:45 splinter rsyslogd: rsyslogd's groupid changed to 103
Does anyone have an idea what's happening here? I've been running 12.04 pretty much since it came out and only started experiencing this problem recently over the past few weeks. It seems particularly strange that the shutdown dialogue appears but then my actions are being ignored by it.
Anyway, I'd be very grateful for any pointers on how to fix this or investigate it better.