2003 Pontiac Aztek security feature

I have a 2003 pontiac aztek and I keep losing power to the guages on the dash. It reads error on the mileage, and all 4 guages go all the way down. Today though after getting it to finally start and get it in gear. When I got back home the engine didn't respond to shutting off it sounded like it was still going even after the key was out and I was on my way inside.