It is a high-failure item, but two years is pushing it. You would hear the clunk if that was the problem. If you aren't hearing any noises, there are four things I can think of. Probably the most likely suspect would be the neutral safety switch. A clue would be it might start if you shift to neutral instead of park.
The next suspect is the ignition switch itself. They develop burned contacts and overheated terminals in the connector, although the circuit typically affected is not for starting; it's the one that feeds the heater fan and power windows. They cause more trouble for people who use the heater fan on its highest speed a lot.
The third thing is the starter relay under the hood. They don't fail real often but it's always a possibility. They can fail two ways. If the contacts are pitted or corroded, it will click lightly but not turn on the starter. That could be intermittent. If the coil of wire is broken, it will not even click. That will almost never be intermittent. That failure is permanent. You might not be able to hear the relay click. A better test is to put your finger on it and feel the click when a helper turns the ignition switch to "crank".
The last thing is a cracked cam on the end of the ignition switch key cylinder. That will prevent the switch from turning quite far enough to hit the starter contact. Everything else like dash lights and radio will still work fine. I've never seen one of those cause an intermittent problem but I suppose it is possible. The dealer has a repair kit for that problem.
A lot of diagnostics can be done right at the starter relay. First swap it with one of the other ones like it. The entire system can be split into four individual circuits corresponding to the four terminals in the socket. A real quick way to test two of them is to bypass the relay contacts. That can be done with a jumper wire when the relay is removed, or you can pop the cover off the relay, reinstall it that way, then squeeze the contact. That should make the starter crank the engine. You can also watch that contact closely to see if it clicks when a helper turns the ignition switch.
Tuesday, June 7th, 2011 AT 2:32 AM