I also know that just by experience, mine did this, and it is a security feature with the keyless entry. if for some reason you have pushed (or yur kids, like mine did for me) played with it. This needs to be reset... if this has been done. all of them are different, but I lock mine with keyless entry, open the door with the key without using keyless entry, start my car, turn it off, repeat. I then remove my key from the ignition..lock my doors from the inside, roll down the window, reach out and open the door handle, this will set off the alarm. or roll down your windows, get out, lock your doors, then reach thru the window and hit the unlock button.  Rather than disarming it with the keyless entry, just start the car with your key. Depress brake, and try it. Good luck.

In the event of an electrical failure, the vehicle can be shifted out of PARK by using the following procedure.Turn the key to the ACC or ON position.Remove the liner to the cubby bin to the right side of the shifter.Depress the BTSI override (2)(BTSI Override) on the side of the shifter assembly (1).While the override is depressed, move the shifter out of the PARK position.Return the cubby bin liner to its original location.

here's the link: http://www.lxforums.com/board/f61/help-car-wont-shift-out-park-113203/