> It has been standard practice for many years that computers are
> required to have RF Interference suppression on all wires leaving the
> case, including the power wires. This includes capacitors between all
> three wires of the cord and the chassis of the computer. One result of
> this is that if the chassis ground wire in the power cord is not
> hooked to ground at the outlet, the capacitors inside the computer act
> as a voltage divider and some amount of the 120VAC line voltage will
> appear on the metal chassis of the computer.
>
> Similar bypass capacitors exist in almost all radio and TV equipment
> going back to well before WW2. (I used to own a WW2 radio that gave me
> a tingle every time I touched it while barefoot on concrete....) This
> is not a short or any sort of fault in the equipment, it is just an
> unintended consequence of the design and NOT having a chassis ground
> wire on the equipment. I'm also not saying that an electrical fault or
> short in the computer is impossible, just unlikely,

aha, this explains the current and many prior personal experiences.  thank you.

> and if the
> equipment was properly grounded, an actual fault in the equipment
> would blow the circuit breaker through the chassis ground wire.
>
> Back in the early 60's, the electrical code was changed so that all
> new construction was required to use grounded outlets in the main
> living area of the house. Some time later this was extended to all
> wiring in the house, including basements. Eventually it became code
> that structures had to be upgraded to 3-wire outlets before they could
> be sold with a mortgage. Because of this it is very uncommon to still
> find old 2-wire outlets in a home. But that doesn't mean the outlet
> upgrade was done correctly.
>
> To upgrade house wiring, the minimum was to replace the 2-wire outlet
> with a 3-wire outlet and screw it into a metal outlet box that has
> metal conduit between the boxes. This is usually sufficient, but if
> any joints get rusty or loose, the grounding may fail.
>...
> I'd be most worried if you see the fault
> light flicker as you plug in a second cord to the outlet,

good point to watch for!

> This ground fault is the most likely reason the computers died,

guess what, on good power my saddest seeming loss is now so far
happily humming.  insha'allah perhaps it's former flaky failures are
now well explained and history.