If any of your new Dells and old Lenovos have expansion slots . . .
You could try to fix the problem by disabling the integrated Intel video through the bios and installing an NVIDIA video card.
You might be able to use the card from the trouble-free system, if you can spare the system for a day to see what happens.
Or you could buy the same NVIDIA video card that's on the trouble-free system by checking device-manager and searching on eBay.
It might be worth a try, since it sounds as if you have several systems that crash.
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As a side note, I wonder if AC's frustrated attempts to reproduce the problem on remote sessions failed because AC's remote program might be using a mirror video driver that sidesteps the bug?
