Macintosh users -- your Mac system can be the carrier of a Windows-based virus or worm even though your system itself is not infected. A few Mac users have recently received Virus Wall warnings saying that a virus or worm they have sent has been removed. In many of these cases the users' Macs have received an infected file from someone else. Even though your Mac itself may not be infected, users of Windows systems to whom you forward an infected message may download an attachment, thereby infecting their systems. In this case it is important to identify the particular file that is infected and delete it as soon as possible.

Mac users are by no means immune from Windows worms and viruses, however. For example, suppose that you run the Connectix Virtual PC (a Windows emulator for the Mac) to run Outlook or some other Windows program. In this case any virus or worm that targets Outlook can also infect your system. You thus need to install the Windows version of Norton AV in your emulated Windows operating system, just as you need to install the Mac version of Norton AV on your Mac. In short, you need to run two versions of Norton AV on your system if it is to be adequately protected. You will also need to keep both updated. To download both versions of Norton AV go to http://www.lbl.gov/download/

All Windows and Mac users---remember that without running anti-virus software (available for free from http://www.lbl.gov/download/) and updating it regularly (at least once a week), your systems are prime targets for virus and worm infections.