Comment # 18 on bug 917411 from macias -

After those freezes computer is dead as brick. No ping ("host is unreachable"),
no reaction to those Rq shortcuts, nothing is in logs. Dead.

Few more things from my memory:
* it is not an issue of VirtualBox -- on all previous freezes, VBox was
present, so I was afraid it was somehow involved, nope, this time VBox was NOT
running, and freeze occured

* however radiotray (idle) is a new factor, it is now present (in comparison to
previous installation), so it is my new culprit #1 :-)

* the freeze seems unrelated to uptime and user interaction, sometimes it
freezes, while in screensaver mode (during night), sometimes right in front of
my eyes while I am typing or moving mouse

* usually the screen is still on, but once I turned on monitor and monitor
claimed there is no signal