general problems of the 1999 Nissan Pathfinder

Since day one, randomly, when I turn the key, the engine appears to have started, but in fact, has not. This usually happens after I have been driving for a while, then park, shut the engine off for a time and when I get back in the car, then turn the key to start. I have complained to two dealers as well as Nissan corportate with no satisfaction. The problem still exists four years after purchase (purchase date 2/99). The danger is that if I think the engine is running and I move the shift, the car can roll if on an incline which can be dangerous. I have also reported this problem to dot with no satisfaction. H e l p.