My Ubuntu 14.04 on Thinkpad T400 just rebooted automatically.
my screen just became unresponsive.
My memory and swap were mostly used, mainly by webpages opened in Chrome and some pdf software.
The cpu and hard drive didn't feel hot. At least shortly before the screen became unresponsive, their temperatures were normal (60 celcius and 40 celcius respectively).
How can I find out what caused its reboot?
less /var/log/syslog is here.