Avid video editors have started reported that when they shutdown their Macs, they will no longer boot up afterwards.  It is not known exactly what is causing this issue, but it appears to be affecting older versions of Mac OS X who have the Avid Media Creator software installed. […]

from https://www.bleepingcomputer.com/news/software/avid-users-are-suddenly-finding-that-their-macs-won-t-boot/