 When that software is updated or changed, because it's so deeply embedded in how the computer functions, unexpected problems can crop up. So companies push out software updates all the time for lots of different reasons, whether it's a security update, a new feature. In this case, CrowdStrike says it was a minor content update for Windows hosts. There was something wrong with that update. We don't know exactly what. But ultimately, that means everyone using CrowdStrike software who are running Microsoft Windows got that blue screen of death today.