Sounds like you have a virus, something like the Blaster worm, that one disables av proggies and will re-boot the system.
Try doing a scan in safe mode also check the virus encyclopaedia at click here
Surface Pro (2017) vs Surface Pro 4
20 groundbreaking 3D animation technologies coming to Siggraph 2017
iPad Pro 12.9 vs Surface Pro 5
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.