2001 Cadillac Deville acting BADLY

My neighbor has a 2001 Cadillac Deville with the 4.6 Northstar motor and everything is computerized. Her car decided to take off on its own today and she had to hit the brakes to keep it from running away. Everything was acting strange. The sensors were reporting seriously out of range numbers for everything from speed to engine temp to tire pressure and the lights were turning on and off randomly. I disconnected the battery for a while to reset everything and the car seemed fine after this.

Is this something that might come back or a random and isolated occurrence? Did the reset solve the problem or will this issue just return again in the future? If so, what is the likely cost to repair? I can definitely understand why everyone wants to avoid these cars.