Since starting this thread, I disabled GhFlt via the Autoruns utility, so I don't get this error anymore.
There's no information at all about GhFlt on the Internet, so I'm guessing it's perhaps some kind of custom service used by Gigabyte technicians for testing / monitoring mobo functions during product development, and references to it are meant to be removed once that job is done ... except that got overlooked, so the call to it is still there in end-consumer products, generating errors in Event Viewer.
Such a scenario would account for a total lack of information about what GhFlt actually is - that it's some sort of product debugging utility perhaps, intended for use by Gigabyte hardware developers only. But disabling it via Autoruns has not caused any ill-effects to my rig.