I used navigation for about 2 hours and 15 minutes straight and the phone shut off from over heating...it was also plugged into the cigarette lighter at the time. I let it cool down and turned it back on....it no longer had any 3G or wifi.
That's weird. I've used mine for GPS nav & music together on 4+ hour drives without any problem.
To Steve, the Incredible is a good phone, but 6 months is a long time in smartphone land. There are newer models with better features. For example, the Hummingbird CPU in Samsung Galaxy is both more powerful AND more energy efficient than Incredible's Snapdragon.