System File Checker is a utility in Microsoft Windows that allows users to scan for and restore corruptions in Windows system files. This utility is available on Windows 98, Windows 2000, Windows XP, Windows Server 2003. Windows Vista, and Windows 7.
Windows XP works very hard to maintain the integrity of the system files on your machine. If you try to replace one of the "protected" files, you may get an informative message that the operating system has put the old approved version back. Not all files are under system file protection and even for those that are, there are ways around it. Occasionally system files become corrupt.
SFC is a good utility to run when you suspect that system files have been somehow corrupted. It validates the digital signatures of all of the Windows system files and restores any that it finds are incorrect. It will use the on-disk cache if possible, but SFC may require that you provide your original installation CD to restore the corrupted files. The following is the How-to:
You need to click Start first and then click Run. After that, type in the following command:
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.
