OBD II real-time monitor causing problems?

[toon_herit]

I've had my Storm White 370Z GT for 2 weeks now and after 5 1/2 years of a 350Z GT with a digital speedo I decided to get a Vi Monitor device that plugs into the OBD II socket. I put it in a few days ago and everything going fine, giving correct MPH, RPM, throttle usage etc., then yesterday a warning light appeared on the instrument panel showing a car bonnet (hood) up, and wouldn't go out.
Anyway I went to the Nissan garage this morning and the technician had a look and said there were quite a few warnings in the diagnostics which they cleared and said that it was common when you use third-party monitoring devices that plug into the OBD II socket and I shouldn't use it.
Apparently they've seen it on GTR's and they can even cause issues with external lights.
Anyone else use (used) a similar monitoring device and had the same problem?

Cheers, Paul.