Using the System File Checker

You 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