I am trying to complete the "Create a hydrologically correct surface" exercise from "Introduction to Surface Modeling Using ArcGIS 10" course on ESRI's web training. I have followed the steps in the exercise through Step 4 (Create a surface area using feature data), which involves running the Topo to Raster tool. However, when I run the tool, it runs until it gets to the point when the status bar says "Topo to Raster 100%" but it never actually finishes and no Elevation file ever shows up in the target geoDB (in this case, Scratch.gdb). We tried this tool from another machine in our office and had the same problem. It just gets hung up and never finishes. Does anyone have any idea how to fix this problem? Both of us have ArcGIS 10.