The first variant of this virus appears to have been written to force TBScan to use the DOS file system and ignore the contents of Anti-vir.dat. It is also known as the "Thunderbyte Killer" due to the text "The Rise and Fall of Thunderbyte-1994-Australia. You Will Never Trust Anti-Virus Software Again!!", but it also attempts to avoid detection by F-Secure anti-virus products and Norton Antivirus.
Lemming has been reported to be widespread in Australia.
There are few known variants.
Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.
More information on the 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.