Microsoft spent several days investigating claims by security vendor PrevX that the company s latest security updates had caused a registry problem that was in turn causing some Windows machines to display a black screen. The Microsoft Security Response Center could find nothing in the updates that was causing the problem. Microsoft security officials said that the black screen problem is seen on some machines that have been infected with malware, specifically the Daonol Trojan. PrevX reversed course this afternoon, saying that it had been working with Microsoft to find the root cause of the issue. It appears that the problem was caused by a characteristic of the Windows Registry related to the storage of string data
Source: https://threatpost.com/black-screen-death-not-related-microsoft-patch-120109/73187/