Running Windows 8.1 with all current updates. Just updated Lightroom 5.7 to Lightroom CC (2015). Lightroom CC causes frequent reboots of windows 8.1 with no error message or warning, making Lightroom unusable. I am a professional photographer and depend on Lightroom to earn a living. I have uninstalled, then re-installed the update. I have logged out of CC and logged back in. None of these has resolved the issue. Please let me know what other info you need to troubleshoot this issue.