An error caused usually by a corruption of the user file. When you get a data corruption there is no systematic, orderly, explainable way in which it happens. It is a random occurrence which happens for various reasons such as:
Power failures
Hardware failures
Network failures
Power dips
Power surges
Unstable or incorrectly setup networks
Poor hardware
Windows errors
Incompatible drivers
Incorrect shutting down procedures
It happens randomly and its quite impossible to pinpoint the exact cause, so in order to prevent it from happening in the future, all the above would have to be checked.

To fix the problem, you will need to do the following:

Restore a backup or send the data for fixing

   Restoring a backup
- In Pastel, click on File...Restore and browse for to the location of the backup
  file and click Process
- You will receive a warning message, click on OK if you wish to overwrite your
  current company information with the backup
- Once the backup is complete, click on Close