A weird thing has begun occurring on my 2000 S430. From time to time when I go to start the car absolutely nothing happens. It does not turn over at all. However, if I return the key to the off position and go to try to start it again it starts right away. There appears to be no effect on driveability or performance. Just seems that about 50% of the time I have to try to start the car twice before anything will happen.

Any ideas on where I might start?

Thanks!