Crash Recovery System

If 3ds Max encounters an unexpected crash, it attempts to recover and save the file currently in memory. This is fairly reliable, but it does not always work: the recovered scene could be damaged during the crash.

The recovered file is stored in the configured Auto Backup path. It is saved as "<filename>_recover.max" in this path. It is also placed in the INI file as the most recently used file in the File menu. This makes it easy to return to the file, if you choose to do so.

The crash recovery system identifies when something in an object's modifier stack is corrupt. In these cases, the corrupt object is replaced with a red dummy object to maintain the object's position and any linked object hierarchy.

Note We recommend that you not rely on this file-recovery mechanism as an alternative to good data backup practices:

• Save your work frequently.
• Take advantage of automatic incremental file naming: Go to Customize menu > Preferences > Files panel > File Handling group, and turn on Increment On Save.
• Use File menu > Save As, and click the Increment button (+) to save incremental copies of work in progress.
• If you are forgetful about saving, use the Auto Backup feature. Go to Customize menu > Preferences > Files tab > Auto Backup group, and turn on Enable.

source: Autodesk 3ds Max Help