Have you tried clearing out the cache files, that seemed to work for other people. Also, you identify two seemigly different outcomes.. A Crash, and your computer turnign off are two things to most people If the application crashes or window crashes it can restart the computer with a seriose error, but if your system turns off and stays off when running scence detection for s while its more likly its over heating. I have noticed this process takes significant GPU and Memory, my CPU workload was light but that might be because I have 18 cores, less cores might be working harder. Either way, check your thermals, clear out the cache and see what happens. also, make sure you are in fact at 14.4 and not runnign the beta for some reason.
if all that fails, maybe others will have some ideas.