Actually, it was a much different problem.

What I discovered was that I had dim'd the counters as Integers, but on
one occasion,
it just happened the upper bound of the 2nd use of the counter happened
to be larger than 32,767 (the upper limit of an integer) and so the
code was just pushing through the For Next loop ignoring the For and
the Next. Once I changed the Integer statement to Long, it worked fine.