When working in the lab, reboot the machine before you begin working. Just hit return when you see this window. On a Macintosh, at the Mac Desktop, select Special and then Restart . If working on a collaborative effort where a disk is placed in machines that may not have virus protection, it is important you scan the disk in an anti-virus program before you place it again in your home machine. Finally, once you have anti-virus software, it is important to update it at least once every month.
Most companies provide updates on their web sites.