I am running NIS 21.6.0.32 on Windows 8.1.1 Pro x64 and after a re-boot (restart or shutdown, fast start disabled) sometimes NIS does not appear in the Notification tray. And sometimes it appears but is totally unresponsive. I have tried uninstalling and reinstalling via NRT and downloading. I have tried setting the boot option to off and to aggressive, but NIS cannot be relied on to start cleanly. Can anyone tell me what else I can try to get this thing working as I am reduced to using Windows Defender at the moment? If any further information is required please let me know.