I have a Windows 8.1 Lenovo Yoga 2 Pro that has been having this problem for about 3 weeks now. I believe it was due to an interrupted system update. I originally solved it by performing a system restore to a restore point from before said update. However, Windows eventually deleted that point automatically (should've disabled that. Whoops). Now, the only solution I have that works is to first revert the pending update from command prompt using
dism.exe /image:C:\ /cleanup-image /revertpendingactions
and then booting with driver signatures disabled.
However, this is unfathomably annoying to have to do every 5 days or so every time the system updates, as well as possibly risk-posing since my computer can't install any windows updates whatsoever. If anyone has any idea how to resolve this issue permanently, it would be greatly appreciated, but this solution at least renders my computer at least somewhat usable again.