I had the same problem with my windows 8.1 pro system. Something was corrupt in my WinSxS folder.
Since I had a Windows 8.1 pro vm also (I always apply new updates here first before my main system), I copied the WinSxS from there to another drive on my main system having problems, and ran this command,
Dism /Online /Cleanup-Image /RestoreHealth /Source:H\WinSxs /LimitAccess
This was able to fix my problem, repairs competed, now both sfc /scannow and Dism /Online /Cleanup-Image /RestoreHealth come up clean.