I had recently been away from the office. Today, when I launched Civil 3D 2006 the "Drawing Recovery" dialog box appeared. It states...
In your previous work session, the program unexpectedly failed.
Information has been gathered from the drawing files that were open
at that time.
The Backup Files list displays the backup files that are available.
Double-click the files on the list to open and compare their contents.
Once you determine which file contains the best backup data, use
Save As to specify the correct folder location and rename the file.
There is a checkable box to.... "Don't show me this again" and lastly there is an OK button.
In the Drawing Recovery palette and files related to the file that requires recovery would be listed. These may include the .DWG file, the .BAK file, and the .SV$ file (the autosave file). The user can then see details of the file(s), and also a preview. As the message above indicates double-clinking on one will open it. Once the appropriate file is saved that file and it's related files are removed from the drawing recovery palette.
Clearly, this allows the recovering process to be done with greater confidence.
Oh, I almost forgot. You can open the Drawing Recovery palette at any time with the DRAWINGRECOVERY command.