Stealth viruses are designed to hide on disks to avoid being detected by virus scanners. You must block stealth viruses from hiding, so your scanner can find and remove them.
Steps to remove stealth viruses
Update your anti-virus software.
Save a copy of your virus scanner onto a clean floppy disk. (You might need this backup file if the scanner on your hard drive is infected.)
Insert the floppy disk into the drive in a locked position; this should block a virus from hiding within the floppy drive.
Run your anti-virus software. If the clean, locked floppy is in the drive, you should be able to detect and remove a stealth virus.
Check if your scanner program is infected. And if it is, use the backup program on the floppy to scan for viruses.
Shut down your computer to clear the memory, and then reboot. Now that the virus is out of the memory, your computer should be safe.