I am running Illustrator 10.0.3 under Windows 2000. I am drawing a map in which I trace lines from a placed layer of a scanned map. After I draw the lines, on a different layer, of course, with the pen tool, I convert the paths to outlines, and then I use the pathfinder tool to join the paths so no overlap is visible. (Picture a street intersection where each street is represented by two parallel lines. The intersection should be clear of any lines.) At some point, some of the lines simply disappear. In the outline view, they still show up, but in Preview, they are invisible. Highlighting them still shows them to be in their original color. But I can't see them! Any ideas? Thanks!!!