I'm trying to help my Dad with a question about his car...It is a 1997 Grand Prix, he states that sometimes my mom will drive the car somewhere ( approximately a 1/2 hour or so ) , turn it off to go inside somewhere and when she comes out, it will not start...This has been a random action, does not do it all the time. Any suggestions?
An intermittent no start condition can be a lot of things.
When you turn the key does the engine crank over, or not? It makes a big difference.
If it's not cranking it could be a bad starter, or a problem elsewhere in the starter circuit. If it cranks over but doesn't start, it's a whole different ball of wax. You have to find out if you're losing fuel or spark.
It can take some time to duplicate a tough intermittent problem enough to track it down. It may be a good idea to have technician scan the computer system, to see if any trouble codes or incorrect data can lead them to the cause.
If I had to guess, the Powertrain Control Module (PCM) would be at the top of the list. Even more so if the "service engine soon" light is flashing when the problem occurs. The light should always be ON with the key on and the engine not running.