The System File Checker gives an administrator the ability to scan all protected files to verify their versions. If System File Checker discovers that a protected file has been overwritten, it retrieves the correct version of the file from the cache folder (%Systemroot%\System32\Dllcache) or the Windows installation source files, and then replaces the incorrect file. System File Checker also checks and repopulates the cache folder.

If the cache folder becomes damaged or unusable, you can use the sfc /scannow, command to repair its contents.

More in this article here: ??????Scannow SFC

Regards

Marc Liron
Microsoft MVP
www.instantvista.com