It sure sounds like the 'voltage error" message is causes by the bike shutting off, and not an actual issue with the voltage regulator.
With it just idling, try and wiggle the wiring and connectors by the steering neck, and especially by the Dyna Module. I have no reason to suspect it per se, just that it's aftermarket and would cause it to die. I'm thinking it's more of a vibration problem, and would like to minimize the "re-testing phase". I can't say I recommend 9K rpm blasts in neutral (or on the street when it's expected to die[sad]
edit: wiggle the kill switch and tap the housing as well, maybe yanking on the bars is causing it to momentarily open or ground the circuit.
I'm trying to think of all the stuff that happens when you're really gassin' it