why the speed display be wrong I use the 1450 for about 1 month , this week , I find several time , that the speed rate be not correct . it be very terrible . i do not know why , I will have to restart it . when the wrong occur , the voice message will delay , so , I miss some intersection . it be dangerous for I to adjust it during drive . by the way , the map have be update . and , in some area the road be under construction . the GPS do not know .