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.