I have a 1999 Cadillac Catera which is not starting back up after a 1hrs drive.

What is your question?

This car generally drives great but if the car is driven for more than 45-1hr or has been idling a while, it doesn't start back up if turned off until it seems like the car has cooled down maybe...after this it starts right back up. I took it for a check and repair and was told it was definitely the alternator and had that replaced but the problem persists...any ideas as to what is the actual problem? No indicator lights are illuminated...radiator recently replaced after fender bender. New battery. Starts again b4 a cool off with a jump from another vehicle. about 45,000 original miles on car.