started getting an intermittent issue , display said "service anti theft system"

Thanks, I have been talking to a mechanic friend I was able to give him more info over the phone. He feels since its an intermittent starting problem and when it acts up no dash lights come on its either the ignition switch or the relay or the wiring harness! he said the lights flickering is a separate issue probably the voltage regulator on the alternator since there is a GM service bulletin and a service kit available (which I ordered) for that issue and also there was a recall on some GM cars for ignition switches. I need to call the dealer and have them run my vin! seems Uplanders have a few electrical glitches he advised checking all ground connections even running my own grounds from the battery to the chassis engine and body to give extra continuity being the vehicles age!