Why fter a few hours driving would it slip into neutral from drive?

What is your question?

Stability System Disabled error for months now, once went into 4WD on it's own. Then after a 3 hour drive it went into neutral at 45 MPH. Could get it to reverse from a parking spot but not go into drive. Dealership found nothing, changed transmission fluid upon request. Driving now but only an hour at a time. So far fine. But I have a trip to make and don't want to destroy transmission.