Is this a new car? Has anything changed recently? I had some mce Iboxs that about once a month a car would be in the overhead. We had just picked these cars up after their one year warranty period ended from the company that did the installs. It was always in the morning, always an empty car. I went through everything possible. Brought weights out, setup some advanced features on the drives trying to rule everything out. It was a software issue. This job was setup to park a car at the main floor, once one was there it'd park one in the basement, once there was one there if there was still no demand itd park one at the top floor. They had a glitch in the original software that sometimes (once a month so 29 successful days) when it was sending the car to the top to park it literally just lost track of where it was and went into the overhead.

I wish i had more info on 411s for you but my thought is check anything that changed. Did they program it to park a car on the bottom floor, did someone just add card readers or security to the car? Very well could be a software issue too.