/SCANNOW – Scan all protected system files immediately.
/SCANONCE – Scan all protected system files once at the next boot.
/SCANBOOT – Scan all protected system files at every boot.
/REVERT – Return scan to default setting.
/PIRGECACHE – Purges the files cache.
/CACHESIZE=x – Sets the file cache size.
/? – Display help at the command prompt.
How and when to use it?
After update that went wrong.
Windows update sometimes causes corruption of system files, yes it is!
After virus infection
No doubt it can ruin every file including system files.
After installing/updating windows driver that causes system error.
Digitally signed files/application are allowed to replace/update system files but this also causes system file corruption
Or simply everytime a system file has been corrupted.
This tool can be executed everytime you want so if you feel you need it then use it.