Hi, Sorry for creating such a thread. But, this is really a problem for me. I have a Windows 8 pre-installed HP envy 4 4-1215dx ultrabook here which for some reason keeps going on with Window 8 restarting loop. It shows Windows is automatically repairing and then FAILED message with "CRITICAL_PROCESS_DIED". I have no rescue disk or system image ready with this ultrabook. I tried disabling secure boot and boot a windows 8.1 usb drive, but it cannot boot into. Shift+F8 for safe mode also not working. When I tried to boot with a Windows 8.1 usb drive, the error says "Selected boot image did not authenticate. Press Enter to Continue" Is there a way, to do a system refresh or system restore and is there any rescue iso available? Thanks in Advance.