Hi,
Everytime I disconnect the battery the car alarm will be reseted. Now I had written down the procedure how to initiate the remote keys.

Here is what I have found about the anti theft alarm and how to inititate the fob keys:
Chrysler Crossfire: Anti theft alarm

Also the radio can have codes that must be entered, not in my case with the stock radio. Some models maybe have to reset the steering wheel what I have read. But that had never happened to me. Maybe different makes, my car is a 2005 Chrysler Crossfire.

/Lars