The interesting observation is that the second unit didn't start doing this until you re-installed the first unit, and I assume that some of your wiring was moved/re-configured at that time.
Another thing to look at is the USB cable connection. Something may have gotten torqued or pulled, leaving it with an intermittent connection issue. If you have solenoids or other vibrations in the machine, it might be enough for a momentary disconnect. I would try wiggling the connection a bit to see if you can re-create the intermittent issue.
Since you indicated that certain events seem to cause it to occur, you should also go over any wiring and devices connected with those events with a fine toothed comb. It may be that there is power backfeeding to the LED-Wiz somehow, which would definitely be a bad thing. If you want to try to to pin this down in email, I'll do my best, but issues like this one can be tough to troubleshoot from afar.