at this point, it is looking increasingly as if my "reset the border on nameplate hide" functionality (aka "de-initialization", trying to disable border graphics on a nameplate as the WoW client recycles it, so that when it is used again it does not have a border) is what is/was causing this problem.
i put all the original border control code back in (i.e. the code we were fiddling with in this thread), but left the "de-initialization" code disabled, and i have not been able to produce a crash under any circumstances.
so it appears that changing the backdropTable on elements associated with a nameplate that is in the process of being hidden is a "no-no". however, it appears i can safely set the border color to something with 0 (zero) alpha while the nameplate is being hidden (which should have the same basic effect).
all the other symptoms related to nameplate initialization (using edgeSize and etc) definitely interacted with the problem, and unfortunately Aloft is indeed able to crash the WoW client intermittently by engaging in some/all of these things, but i think the workaround is not to reset the backdropTable on a nameplate that is in the process of being hidden. (like the old Henny Youngman joke about the man who goes to the doctor.)
anyway, thanks very much to all who contributed. it was all worth doing. if the problem crops up again, i will pick up where your suggestions left off
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