have you got a spare key card ,if so try that key card and see what happens ,also check that the card reader is not loose when you insert the key card, also check the battery voltage of the key card battery, the voltage rating is printed on the battery,also check when you have inserted the card and press the start button , make sure the red led on the instrument panel is not flashing , if it is its possable its a key card problem , also when you press the button does the ignition come on as normal and then it tries to to start , you need to see in more detail whats happening and whats not happening and how often it happens from the point of inserting thecard and pressing the button due to the fact that theres a few things that can go wrong ,hope that helps .
mark
April 2008