There are several things that may indicate the presence of a virus on
1. Unexplained file growth in EXE and COM files may indicate an
2. Programs that used to work now return with some type of error
message and fail to work at all. This may indicate an overwriting
virus. Some common messages are "Program to big to fit in memory"
or "Unknown Command" and other similar messages. Thes should make
3. Unexplained directory changes. If you execute a program and then
find that you are suddenly in a different directory, this may
indicate that a virus has been hunting for files to infect.
4. A decrease in available system memory. You should know how much
memory is usually free on your computer. If this number drops, it
may indicate a TSR virus. This does not always work since some
viruses do not protect the memory they use.
5. Unexplained ChkDsk errors. Stealth viruses will cause you to get a
CHKDSK error because they are altering the info before it gets to
CHKDSK. If you do a CHKDSK /F under this condition, it could CAUSE
considerable damage to the directory structure when in actuality
nothing was wrong in the first place.
6. Unexplained disk access. If the floppy or hard drive begin to light
up all of a sudden for no reason, it could mean viral activity. It
could also mean that you are running a disk cache with staged
7. An overall slowdown in system activity. Programs may take longer to
execute than normal.