This is a typical boot sector virus. It sometimes displays a 'Runtime error' message.
Defo was reported to be in the wild in several countries during summer 1996.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
More information on scanning and removal options available in your F-Secure product can be found in the Help Center.
You may also refer to the Knowledge Base on the F-Secure Community site for more information.
Description Details: Mikko Hypponen, F-Secure