By Bill Grogg

Even while using good virus prevention methods, you may still experience damage from an unknown virus, a new trojan horse or worm, or just a corrupt program or computer crash.

Since your data is the most valuable stuff on your computer, make sure that it is backed up regularly. In my experience, very few people regularly, if ever, back up their data. Many have to experience the loss of irreplaceable data before seeing the value a good, current backup.

When you are sure your system is free of virus infection, make a bootable floppy disk and copy to it any system tools that you might need for data recovery or system repair. You might also want to add your anti-virus software to this or another disk and make sure that these recovery disks are then write-protected.

Since damage can occur by means other than a virus (such as corruption of files or the file system), it is also a good idea to periodically check your disk for logical or other errors which may occur due to program bugs, system lockup, power loss, and other problems. This can be accomplished at the very least on DOS, Windows, and Windows NT systems with the CHKDSK and/or SCANDISK programs. An advanced disk utility such as the Norton Utilities or PC Tools will have more thorough tools (such as Norton Disk Doctor or DiskFix) to check for and repair these kinds of errors.

Another possible cause of data or program corruption is physical problems on the hard disk such as bad clusters. Advanced disk utilities such as those mentioned in the previous paragraph have programs to scan the physical disk for unreadable errors. In some cases, if these are found where data resides, the data may be able to be read after a few attempts and then rewritten to a good cluster elsewhere on the disk.