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!

by in Englishtown, NJ on July 27, 2011
2 answers
ANSWER by , May 22, 2012
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.
ANSWER by , June 29, 2013
Engine Control Module. Had same problem, also trunk would not open.