Balloonmeister

I have a 2102 Cayenne S. When purchased new, we had the dealer install the plastic "key" in the ignition switch so that all we would have to do is get in the car with a key fob and start it up, without inserting the key fob in the ignition. I have had two instances now where one of the key fobs would not be recognized by the car. Today, my spouse, who drives the car almost exclusively, went out to go run an errand and the car would not start, nor would her key fob lock or unlock the doors. I then tried my key fob, which hangs on our utility room key board when not in use and my key fob would not unlock, lock or allow the car to be started.
Having had a problem similar to this a few months ago (with the same key fob not first working), I had her take her key fob and drive another car away from our house. She was perhaps 500 yds away and my key fob would then lock and unlock the car. Thinking that I had cured the problem (as we had used my key fob to unlock the car the last time hers didn't work [thankfully I had it with me that time]), I had her return to the house and try her key fob and it still wouldn't work. Surprisingly, neither would mine again! Thinking at this point that something must be seriously wrong with her key fob to the point that it was actually interfering with the operation of my key fob, I decided to take a time out and came back to the problem about 30 mins later. Lo and behold, now BOTH sets of key fobs will lock, unlock and start the car.
Given that this is my spouse's car, I am very concerned that she may find herself at some point unable to even unlock the car, much less start it. Has anyone else experienced this problem and, if so, what was the solution? I did speak with my local Porsche dealer service dept after the first instance and their answer was "Well, these are pretty sophisticated electronic systems and sometimes they get confused. ..." Any help would be greatly appreciated.