 In tech circles, it's known as the blue screen of death, a screen that appears when booting up your computer that tells Microsoft users that Windows didn't load correctly. Under that, there's a button to restart, which just takes users back to the same blue screen. This boot loop, as it's known, has affected computers at thousands of businesses, including hospitals, banks, and airlines. It's been tied to a software update sent out by cybersecurity firm CrowdStrike. Mike Dubosky, ABC News.