The SureSave utility (reactor) automatically saves changes in your drawings even in cases where standard Save, Close or AutoSave fails. SureSave will keep a backup copy of your current drawing (to a specified folder) on any Save, SaveAs, or Close operation (even if you click on 'Save changes [No]' by mistake and even if the standard save operation fails because of a disk error). It will also preserve the latest AutoSave (SV$) file (usually deleted by Autodesk® AutoCAD® on exit). You can also save automatically after every N AutoCAD command.
See more at http://www.cadstudio.cz/en/apps/suresave/