Hi there guys.

I am trying to solve a problem a friend of mine has in her Fiesta 1.3 Duratec (2004).
It starts up perfectly in the morning and runs with out any problems but once it warms up and is switched off, it doesn't start again. Once left to cool for a bit, it starts again without problems. The engine check light is not on.
I'm assuming it's one of the sensors giving incorrect information.
I changed the pugs quite recently so I doubt it's them.

Any ideas?