If you're using one of McAfee's antivirus suites, and you happen to lose Internet connectivity recently, then you're probably an unfortunate victim of a software glitch found on some of its latest updates. The bug has affected both home and enterprise users, although it is said that it did not send enterprise users offline.
According to the McAfee Corporate Knowledge Base's article, the affected DAT or virus definition files are numbered as 6807 and 6809. Preliminary workarounds for users of McAfee's VirusScan Enterprise 8.8 corporate security software are also available on the same article.
McAfee has released a hotfix as well as several workarounds to resolve the issue. In some cases, it is recommended that users uninstall and re-install the antivirus application in order to get the problem fixed. The initial patch included DAT 6809, of which the security firm has since removed and replaced with a smaller version on Tuesday. A "full DAT update" is still required after the hotfix is applied.
Based on this FAQ, the bug has "resulted in some customers experiencing a loss of Internet access and/or receiving error messages from McAfee".