sefann,

it explains why it shows that you moving in some different city on the map. you do not have GPS antenna connected, and now what happening is: your navigation has not only antenna for the positioning information but also compass and vehicle speed information. this is for passing under the brifges and tunnels and in downtown of some cities where the connectivity to the GPS satellites may be interrupted. once signal from gps is lost your navy starting to use last known vehicle position + compass direction of motion + vehicle speed to calculate your trip and show position on the map.

get the antenna off ebay and you will be able to have your navigation working properly
by the way if anyone is interested you may check here about the navigation retrofits for E70 and other BMW: www.bmwretrofit.com
these guys do it in Canada and can probably also help you if needed.