When I move my finger across the screen to move the map on my Nuvi 1450, the map moves in the general direction of my finger, but makes random motions as I move. When I stop with my finger on the screen, the map oscillates in various directions. When I remove my stopped finger the map zooms off in a random direction so that what had been in the center of the screen is often now off screen. I sent the first 1450 back to the seller because of these symptoms and received a new replacement, which is now displaying the same behavior. I have reset the sensitivity of the screen, to no avail. What is causing this? Is this a known defect in this model? Is there a fix that I can perform?