DareBee,

I'm leaning towards the lower the baud rate one notch, but I'd also check the grounding of the cable. Use a meter and check that the ground is only on the correct end of the cable connection, or you could get spurious signal noise.

If you can correlate a code problem to the lights, I'd be real suspicious of a grounding problem.

(I've been blaming myself for code problems...but that light thing might come in handy!!)