The infamous main relay.
Although you should be able to restart the car after 5-10 minutes.
I don't know about a few hours...


Here is something.

Locate where your main relay is and make sure it's accesible.
Now go on your drive and stop the car.
When you go to restart and it dies like your describing tap the main relay and it should start.
If it does then you know for sure that it's it.

The problem is that the contacts become loose from the warmth.
You can actually repair it if you know how to solder.

http://www.markl.f9.co.uk/howto/elec...main-relay.htm

Here is an in depth look at the relay

http://autorepair.about.com/library/.../aa010301b.htm