The 'FakeFormat' is a trojan program. Being run it overwrites boot sector and both FAT copies of diskette in drive A: assuming that there's a 1.44 mb diskette is there. After that a diskette boot sector contains a stub that will output:
This is a DATA disk only; Insery system disk, press any key when ready.
The trojan waits for keypress and if CTRL + C combination is pressed exits to system, otherwise it loops (starts ist code from the beginning).
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.