Customers running the latest versions of Windows client and server on UEFI-enabled machines have reported issues during startup that prevented the computer from booting properly. Microsoft confirmed that, in certain scenarios, Windows 7 and Windows Server 2008 R2 on UEFI-enabled machines wouldn’t boot, but instead freeze, displaying nothing more than a black screen to end users. Per the ingenuity of Windows users, these types of errors are often dubbed Black Screens of Death, after the infamous Blue Screens (also of Death – BSOD) errors. “This issue occurs because one of the following apps doesn’t clean up all page table entries for pages that were freed: Windows Operating System Loader (Winload.efi) application; Windows Resume Loader (Winresume.efi) app. When Bootmgfw.efi application tries to clean up these page table entries, this app accesses an invalid memory address and causes an access violation exception. Note The Bootmgfw.efi application is the Windows Boot Manager application,” said Microsoft in KB981275. A supported hotfix is available from Microsoft.