Starting Problem with 2000 Boxster S
 

There is no noise after I turned the ignition. The dashboard lights all lit up but the started motor did not crank. It was complete silence.

I have changed the battery, starter motor, DME and immobiliser but problem still happens intermittently (about 95% of the times).

I am so stuck and would appreciate any advice.

Ignition switch
 

or a sensor that determines if the clutch is in, the gear box is in neutral or the steering wheel is locked? I've had the same problems and it was a gear box interlock mechanism. I wiggle the steering wheel and the gear lever and the next time I try it starts. Took it into the dealer and they sprayed something on it and gave it back no charge! Contact cleaner? Much better now.