Stopping the 'Cover was previously removed' alert on Dell computers

Symptoms
After you remove and replace the cover on some Dell computers, the following message is displayed at the next system start-up:ALERT! Cover was previously removed.
Cause
Some Dell computers have a chassis intrusion switch will detects when the cover has been removed. This acts as a security measure against hardware tampering.
Resolution-Technicians and Advanced Users ONLY!
To reset the chassis intrusion detector, enter System Setup (BIOS settings), select System Security, and reset Chassis Intrusion to Enabled or Enabled-Silent.