Bill B wrote in news:5aydndHLo5XMvIXZRVn-
:


AC inducts current into nearby conductors real well, so it was loading
the ground wire, no longer connected to a ground, with lots of juice.

Um, no. You'd need miles of wire to induct any appreciable amount
of charge into a parallel unconnected wire at the frequencies power
lines work at.

Since the case of the computer is directly connected to the ground
lead... Replacing the cord solved the problem.

Something else was also connected to the ground lead - quite likely
the power line neutral (the "white wire" - I'm guessing this since
you've stated the extension cord was defective). As you observed,
when the far end of the ground lead wasn't grounded, this provided
enough charge on the case to give you a tingle.

John