This is a typical boot sector virus. It activates when a machine is booted on the 19th of August, displaying a Russian flag on the screen. In 1991, this was the date of the communist military coup attempt in Russia.
The virus also contains the string "Ekaterinburg" at offset 17Ah in an infected boot sector. The text is encrypted.
Allow F-Secure Anti-Virus to disinfect the relevant files.
For more general information on disinfection, please see Removal Instructions.