Before this problem happened, my key fob was about 1/2 block (200 yds) away from the vehicle and could have been pressed. I am not sure if it was pressed, as it was going through a security screening checkpoint at the courthouse. Not sure, but perhaps this could have contributed to the problem.

When I returned to the courthouse today I used a different entrance and security screening checkpoint much farther from my vehicle. I requested the security guard to please not push any buttons on the remote, because "I had a Crossfire and they were potentially sensitive". I got a strange look from the guard, but he did not push any buttons on the remote. My car and remote and alarms all worked fine when I returned to my car today.

 

I had a similar problem with my recently acquired 05 roadster.
I removed the old batteries and waited too long before installing the new ones.
The instructions in the owners manual describes how to re-sync the key fab with the car - it works.
Then 2 days ago the key would not work, so I followed the same procedure and now it works fine.
Perhaps I should carry both keys when driving!
Doug 62

 

Thank you for your suggestion Doug. My car has continued working fine since I disconnected, and then reconnected, my battery. But I will try your re-sync suggestion if the problem happens again.