I have an ArcMap Project in the WGS_1984_UTM_Zone_40N coordinate system (for north-east Iran), using data and shapefiles from different sources. For the xy-data and the image I use as basemap, I defined the above coordinate system which the map-image is originally in as well as a DEM of the area. Other shapefiles (roads, rivers etc.) had no coordinate system defined. I defined it by creating a new feature dataset and adding the files into it. However, even though all of my data now have the same (geographic and projected) coordinate system, they are shown very far apart. If I try to align them, e.g. by clicking "set data source" in the properties window or by creating links in Editor-Spatial Adjustment, the shapes of the features change completely. I have this problem no matter the order in which I add the data into a new map project. Does anyone have a hint on what the problem might be and how I could overlay the data?