I believe I have narrowed down the problem. My wife's key has no problems, it will start up immediately ever time with her key. My key unlocks and locks the car the just fine and turns in the ignition just fine but will only crank the X5 about after 6 to 9 tries. So it seems as though something is dirty or a loose connection of some kind within the key. I am the main driver of the X5 so my key is constantly in and out pockets, jackets, etc... but my wife's key is rarely used. There does not appear to be any dirt or lint in or on my key though. Any ideas about this?