There's a two piece spring loaded plastic pushrod in the shifter that breaks and causes one or more interlock issues e.g. can't start, can't remove key and/or non functioning shift lock button. If you can pull your shifter from D to 2 without pressing the unlock button on the front of the knob you probably have a broken rod.
I fabricated a replacement metal pushrod. The only other alternatives are a full replacement shifter assembly, $$$, or snip the cable and live without the safety features.
If you have interlock issues be sure to report it at
http://www.nhtsa.gov/