Using the System File Checker

u can run the System File Checker to verify protected system files.

Command line switches are:

sfc [/scannow] [/scanonce] [/scanboot] [/revert] [/purgecache] [/cachesize=x]

    * /scannow  - Scans all protected system files immediately.
    * /scanonce - Scans all protected system files once.
    * /scanboot - Scans all protected system files every time the computer is restarted.
    * /revert - Returns the scan to its default operation.
    * /purgecache - Purges the Windows File Protection file cache and scans all protected system files immediately.
    * /cachesize=x - Sets the size, in MB, of the Windows File Protection file cache.