I just thought I'd do a "Reset All Meters"... but it didn't do anything.
But another curious thing happened... I dropped down those Vertical Faders by about -30dB, and did a Mixdown, and the resultant file was as normal and a good level.
(Note: when I do a Mixdown, I choose "Buses", and select only Master... as opposed to "Entire Mix".)
Another Note: I just did another mixdown, but chooosing "Master Output". and with the faders down so low, the mixdown was indeed very very low in volume.
So now I need clarification on these variations, and which Mixdown option is best.
Thanks