I know I'm late to this party (for those that know me, that comes as no surprise), but I had this problem a couple years ago, and it was very hard for me to find the fix. But this is a great trick to fix corrupted Windows 7 or 8 system files. So, for future viewers, I'd like to leave the following gift:
You must be connected to the Internet, however. From administrator-level command prompt, type:
dism /online /cleanup-image /restorehealth