For the past few months my home server (running an ascii installation
physically moved from another computer) has been suddenly stopping all
processing about once a month. apparently at random. It seems to stop
instantly, leaving power on and becoming completely responsive to ping,
existing ssh connexions and use of the physical keyboard.

The system log, after a reboot, shows nothing unusual except of course
that there are no log entries for a shut-down.

Can anyone provide ideas about tracking this down?

It could of course be a random rare intermittent hardware error.

-- hendrik