I use Linux Grub2 bootloader as deafault, but I don't start Windows 8 using it. When I need to run Windows 8 I just press ESC (or go to BIOS) and choose Windows.
"sfc /scannow" result:
Beginning system scan. This process will take some time.
Beginning verification phase of system scan.
Verification 100% complete.
Windows Resource Protection found corrupt files but was unable to fix some
of them. Details are included in the CBS.Log windir\Logs\CBS\CBS.log. For
example C:\Windows\Logs\CBS\CBS.log. Note that logging is currently not
supported in offline servicing scenarios.
The system file repair changes will take effect after the next reboot.