Help - Key gets Stuck in ignition

I am having a problem with my 2002 TrailBlazer. When we get where we are going and turn off the car the key get stuck and will not rotate far enough to allow it to be removed. We wait until the driving lights go out and then we are able to rotate the key the rest of the way and remove the key.
When this first started I replaced the battery and it stopped happening for a few days but its back again. The car starts no problems and their is no indication of a battery or alternator problem.
The dealer swears that this is impossible and that the key is not connected electrically in anyway.

Does anyone have any suggestions?!?

I am having a problem with my 2002 TrailBlazer. When we get where we are going and turn off the car the key get stuck and will not rotate far enough to allow it to be removed. We wait until the driving lights go out and then we are able to rotate the key the rest of the way and remove the key.
When this first started I replaced the battery and it stopped happening for a few days but its back again. The car starts no problems and their is no indication of a battery or alternator problem.
The dealer swears that this is impossible and that the key is not connected electrically in anyway.

Does anyone have any suggestions?!?

My mother in law has a 2001 trailblazer that does the same thing, you can hit the gear shift very hard on the right side , hitting it toward the passenger side and sometimes it will allow the key to be fully turned off. She bought the car used last year and this has been a constant probem, the ignition lock selonoid has been replaced by the local Chevy dealer, for a cost of $173.00 and he swares that this will correct the problem, it hasn't. I am thinking that there is a switch or something on the gearshift that is not making full contact. But then I am NOT a mechanic..... KY4LC