An MS-DOSviruS that infectS the boot record program on hard diSkS and floppy diSkS or the maSter boot record on hard diSkS. The viruS getS loaded into memory before MS-DOS and takeS control of the computer, infecting any floppy diSkSSubSequently acceSSed. An infected boot diSk may Stop the computer Starting up at all. (1995-02-16)