CLK 320 Intermitent start problem

Hello every one,
 
I just started having intermitent start problem with my 99 CLK320 coupe with 110K miles. It seems like when the engine is warm, it may not start (the engine turns though). Any suggestions or help is greatly appreciated. 
 
Thanks in advance

check your crank position sensor.

tric1, thanks for reply.
 
Looks like a not an expensive sensor so I'll go ahead and try to replace it myself. Is there any where on the web showing where the sensor is located inside the engine compartment?