If you use McAfee's VirusScan 4.x and have Adobe's new Acrobat Reader 4.0 installed on your system, you may have had an unnecessary security scare. After downloading virus definition file 4.0.4017, VirusScan would mistakenly report that the main Acrobat Reader executable file, ar40.exe, contained the NetBus trojan horse. Though ostensibly an above-board remote-control (and spying) program, NetBus is often exploited as a trojan horse. According to the Data Fellows antivirus Web site (www.europe.datafellows.com/v-descs/netbus.htm), hackers have used NetBus to steal data and delete files from remote users' PCs over the Internet. Luckily, the NetBus scare was a false alarm. An Adobe spokesperson says that Acrobat is virus-free and that updating VirusScan to the 4.0.4019 virus definition file will prevent that false report. For the details from Network Associates, visit www.avertlabs.com/public/datafiles/valerts/vinfo/ar40-info.asp.