If you're system is infected with a virus, you should install anti-virus software to rid it of the intruder, if the anti-virus software can't clean the system, you may have to delete the infected files from your system and restore from backups.
In extreme cases, it may be necessary to reformat your hard drive, destroying all of the data on it. Then you'll have to reinstall your software and data, assuming you have the original software disks and clean backups of your files.
In this case, it's a good idea to install your virus protection software right after installing your operating system (like Windows), so that the integrity of your backup files and original software can be verified.
You might also want to contact all the people that you've recently exchanged information with -- via floppy disks, e-mail attachments, Zip disks -- and let them know your system's been infected and theirs may be infected as well. You'`d want to advise them to check their system for the appropriate virus or symptoms.
