C3) What is the best way to remove a virus?

In order that downtime be short and losses low, do the minimum that
you must to restore the system to a normal state, starting with
booting the system from a clean diskette.  It is very unlikely that
you need to low-level reformat the hard disk!

If backups of the infected files are available and appropriate care
was taken when making the backups (see D10), this is the safest
solution, even though it requires a lot of work if many files are
involved.

More commonly, a disinfecting program is used.  If the virus is a boot
sector infector, you can continue using the computer with relative
safety if you boot it from a clean system diskette, but it is wise to
go through all your diskettes removing infection, since sooner or
later you may be careless and leave a diskette in the machine when it
reboots.  Boot sector infections on PCs can be cured by a two-step
approach of replacing the MBR (on the hard disk), either by using a
backup or by the FDISK/MBR command (from DOS 5 and up), then using the
SYS command to replace the DOS boot sector.


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