Key will not release from ignition, gauges don't register, on 2004 Cadillac SRX

Used 2nd key still same problem has occurred twice within a week apart, always while sitting at traffic light, "service Theft system" light comes on, then traction control light stays on!

Asked by for the 2004 Cadillac SRX
2 answers
Engine Control Module. Had same problem, also trunk would not open.
Have you replaced the car battery? I had the same problem..display went black. I didn't turn off the car until I got into the garage and the key wouldn't release from the ignition. Found out later it was caused by a bad cell in the battery.