Yes, it is normal if you have locked in a location in a some what open area, then move on into a heavily timbered area, obviously with the unit still on, at times you can lose transmission with the sattelites. Just turn the GPS off, move along untill you reach a more open spot and start it on again. Some GPS' s do better than others in limited situations, such as some Magellans I' ve owned, they would regularly give me that problem. I now own a Summit by Garmin, it has done much better in heavily wooded areas. elknut1.