"... it does not occur as rarely as you might think."
results suggest (not prove) that it's something else, not the driver.
and same channels?  It could be, but I see no proof.
for other reasons, this wavetable synthesis problem is a minor annoyance.
of the soundfond and/or the MIDI player and/or sequencer."
else other than a driver problem.  Maybe it is, maybe not.