Sometimes 2010 will refuse to save files, claiming you don't have permission.
AutoCAD 2010 is a major release in Autodesk’s long-running AutoCAD series, aimed at 2D drafting and 3D modeling for architects, engineers, drafters, and designers. Released in 2009, it refined prior workflows with improvements in the user interface, productivity tools, drawing performance, and 3D visualization. This monograph summarizes key features, architecture, workflows, file compatibility, customization, performance considerations, migration and legacy support, typical use cases, common problems and fixes, and references for further study. Autocad 2010
