Original post : Error loading operating system: Fix for Windows XP, Vista, 7.
Press one of these keys to enter BIOS/CMOS: DEL or F1 or F2 or ESC.
Press Pause key at boot to pause the loading messages.
You can also try the solutions from Windows 7.
C:\
bootrec.exe
bootrec /FixMbr
bootrec /FixBoot
bootrec /ScanOs
bootrec /rebuildBcd