As they investigated further, they discovered that the problem was due to a recent update that had been installed overnight. The update had triggered a activation check, and since they didn't have a valid product key, the operating system had become unactivated.
While there are methods to activate Windows 8.1 Pro Build 9600 without a product key, the most reliable and secure approach is to use a genuine product key. Microsoft's stance on software activation is clear: using genuine software helps you avoid malware and supports the software developers you rely on. activate windows 8.1 pro build 9600 without product key