Complete loss of electrical power

[bigeyerah]

I have a 2002 Rendezvous and it completely loses power when I stop the car and turn off the ignition. I can tell when it happened because the odometer doesn't display when I remove the key. If I try and start the vehicle it is completely dead - no lights turn on, there is no sign of electrical power). 6 or 8 hours later the power is restored without me being anywhere near the vehicle. The last time it happened I must have pressed the emergency flashers because at 4 AM I woke and saw the flashing lights and went out and turned off the flashers. Today the car is behaving properly. I have replaced the ignition switch module (the first time this happened and it has been working fine for 4 months) and the battery is one year old. The battery terminals are clean a bright and have never showed any corrosion. The dealer (the first time it happened) found nothing. I changed the ignition switch module at the suggestion of my best friend and the problem stopped for 4 months.