Okay folks!
I finally ended the crashes on my son's computer! No, I didn't phaser the stupid machine...
... a friend told me that he once had an issue with a new motherboard not being able to handle its fastest rated data speeds at its FSB because of a blown cap on the board. It appears that some of these capacitors' function is to smooth out any spikes and irregularities in this signal and without ALL the caps, it cannot smooth out the signals at the highest FSB speed. So he tweaked it down a tad and had no probs ever since.
So I tried it.
So it works!
So now I'm only 90% happy.
This is because, while the whole system no longer hangs, it runs at less than max transmission rates. I had to reduce the FSB speed in the BIOS from the preferred 166 MHz to the current 133 MHz.
I know, I know, the difference is miniscule and should affect nothing... but the thought of it!