Computers shutting down everywhere

I’ve got 6 computers, in 2 states, across 4 clients, all shutting down or restarting randomly… This started happening about 3 weeks ago. There are no similarities between these machines—some I built, some are from other local computer places. None of them have the same motherboard or processor… The only thing linking them is they are all running Windows XP.

I guess this is a cry for help—anyone experiencing the same thing?