[CentOS] Strange new boot problem with CentOS 4 machine

> I have a custom-built PC on which I've been running CentOS 4.x (kept
> up to the latest x) for a few years without any problems ... until
> this week.
>
> Last week I was out of town on an extended trip, so I shut the machine
> down and powered off my UPS, etc.  When I returned on Saturday, I
> turned everything back on, and the machine seemed to be booting
> normally ... and then it just very abruptly turned itself off, and
> refused to power back on.  A short while later I was able to restart
<snip>
Does it croak before or after it hits the interactive option? If after,
hit that I, and step through.

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