GPS confusion

Here is one little story from our Germany Trip:
We rented a car and brought our own GPS system to help us get around. Camille was the great navigator, interpreter of the directions etc. It worked pretty well to get us to Salzburg. We put in the hotel address and it seemed to take us right to it, except it took us kind of past the street the hotel was on. Then it took us kind of around the back side of the city, and then started taking us up hilly old cobbled streets. Before we knew it we were next to an old monastery, on a hill and going towards a very narrow stone arch - people were walking on this path. We stopped, put in the mirrors, and after a few scary stalled starts, finally inched through the arch and on to level ground. We then saw a couple of other cars up there. NO way were we going to go down that same way, and our hotel was NOT up here. When we got our nerve to drive again, we saw a different path (cement walking path that went down the front of the hill. We put Camille in the drivers seat and as we slowly started towards the path down, the GPS glibly announced: "Turn right in 500 feet... you have arrived!" We were on the edge of a cliff beneath the fortress and apparently our hotel roof was just down below us!! HAHA. Here is a photo of the fortress in the last light of day. we later learned that our hotel was in a pedestrian area and the GPS will NOT take a car into a forbidden area.