Car will not start

When you turn key on my car it will not start. It is not the battery Ford did a eec test said pats immobilizer error. No communication with modules on the high speed network needs additional diagnosis. I can start it by using the instructions on how to start your car when the anti theft device will not let it start. Sometimes I have to do the process several times but it always starts after a couple of times. Ford place said it could be $100.00 or a couple of thousand to fix the problem that they would just get rid of it. It is a great little car have had no trouble until now. I bought it from a one owner at the Honda dealership one and half years ago. Any suggestions?