Here is a list of safety principles to follow to ensure that your SuperMemo databases are safe and sound:
1. exit SuperMemo before turning off the computer or before starting an application that might cause an unrecoverable system lock-up
2. keep 2-3 back-up copies of your database files (particularly, after adding a larger number of new items). Do not back up files of an open database!
4. never try to modify the content of database files by means of tools other than those supplied by SuperMemo World
6. keep accurate date and time setting
7. if Database integrity error message appears, (1) create a back-up copy of the database (do not override earlier back-ups), (2) run Tools : Recover and (3) run Tools : Garbage (set the Compact check box on, if possible)