2001 Jeep Grand Cherokee Larado Rebooting

I have a 2001 Jeep Grand Cherokee Larado vith a 4.0 engine (V6) and about 120,000 miles. I started it one day and heard like a pop/spark and the radio time reset but my stations were still set, The Jeep dealership stated I needed a new battary & I bought one and it is been working fine until this morning when I tried to start it, it would not start & I heard like a whining/clicking and sounded like something rebooted, I took the key out of the ingition and reinserted & it started right up and the radio time was reset again, any ideas? This only has happened a couple of times over a 2-3 week period. But everything else works like cruise control, power locks, windows, alarm all factory. : ? ?