nVIR is an obsolete computer virus which can replicate on Macintosh computers running any System version from 4.1 to OS 8. The source code to the original nVIR has been made widely available, and so numerous variants have arisen. Each variant causes somewhat different symptoms, such as: application crashes, printing errors on laser printers, slow system response time, or unpredictable system crashes. nVIR spreads through any nVIR-infected program, but due to the long period of time nVIR lies basically dormant in a host system, nVIR generally finds its way into system backups and is not detected until the first overt symptoms appear. For example, if a disk used in an infected Macintosh is removed and inserted in a second Macintosh, the other machine will become infected if any application o