Is it possible that something smoldering or arcing in the electrical system created the CO? I could imagine something smoldering at a fairly low temperature, possibly not even tripping the circuit breaker or smoking, but still causing enough of a chemical reaction to emit an appreciable amount of CO. Combine that with the human physiology at a cabin altitude of a couple thousand feet and I can see how its possible to end up with some fairly serious impairment.

Anyone know if the level of impairment decreased after donning the O2 masks or were they not on it long enough to have much of an effect?