Key will not turn

I have a Grand Prix, 01, that does the very same thing. And it only seems to be when youre in a hurry I bet!
Im going to guess its the same thing as mine(almost positive it is). Ive heard a ton of pontiacs have this problem with the floor shifter.

Next time it happens, turn the key to run and try pushing the button deal on the shifter repeatedly, and listen for a click. If you dont hear anything after a bit, try tapping the brakes. Keep playing with the button untill you hear that click. Then it is ok for that damn key to come out.
Also, to save your self the hassle, try this. As youre about to put the car into park, be listening for that click. Put in the brake, push the button, put it into park, and SLOWLY release that button. It should click and youre free to go! The key is to go slow and let that click happen, whatever the hell it is.

Good luck I believe that should solve it!

Thank you for the info. I will try this to see if the click is the issue. In the mean time I am taking it to the Pontiac dealer for a relay to be put into the ignition system. It is a recalll item and will be done at no cost. Maybe it will help, maybe not. But I have found an interesting way to get by this. Under my steering column there is a 1 1/2 X 3/4" popout panel that conceals a manual override for the steering lock! I know it doesn't address the problem but it sure is easy to use. I just put my finger into the hole and depress the pin and AMAZING. The key returns to off and comes out every time. If your year has this, it may work for you. Thanks again for the info, and have a great day. Keith