Using sfc /scannow for your windows repair

Self File Protection System In Windows

Windows XP has the ability to protect itself from system instability caused by the overwriting important system files. This is a problem with Windows 95 and Windows 98. With the introduction of Windows Millennium Edition, Microsoft made a strong effort to stop this from happening. Now, in Windows XP, there is a much better protection of these important files. This system is called Windows File Protection



Windows File Protection is always enabled and allows Windows digitally signed files to replace existing files safely. If you introduce a file replacement in any other way, Windows File protection will overwrite your file!



An important part of Windows File Protection is the command line utility: System File Checker (sfc.exe) This is a great tool for troubleshooting Windows XP problems.

The main reason for using this utility is when you suspect there may be a problem with a Windows XP system file. Perhaps you get a dialog box appear informing you of a problem with a .dll file, or your program will just not load! It is therefore worth checking to see if there are any corrupt system files using scannow sfc.



To do this simply go to the Run box on the Start Menu and type in: sfc /scannow



This command will immediately initiate the Windows File Protection service to scan all protected files and make sure of their correctness, replacing any files that it finds with a problem.



Note : Make Sure That OS CD On Drive.



A box should appear to give an indication of how long the process is taking.

If all goes as it should, any corrupt, missing or incorrect files would be replaced by this process. However, as with most actions in this world, things can go wrong and the following should help!



The most frequent complaint with scannow /sfc is that a dialog box appears asking you to insert your Windows XP CD-ROM to continue.





Why Does This Happen ?



There are several settings in your computer's registry that are checked when you run scannow /sfc.



As stated before, the Windows File Protection constantly monitors for any changes to the main system files. These are usually stored in:C:WINDOWSSystem32Dllcache (C: in most cases is the root drive) The dllcache folder is extremely important so Windows XP hides it from you! To view it go to:



My Computer -> Tools -> Folder Options -> View -> "uncheck" Hide protected operating system files.



There is normally no need for the original XP CD to be inserted as your computer has a copy it can get hold of in this cache.



But, if the Dllcache folder, or part of it, has become corrupted for some reason then you will be prompted for the XP CD - so your computer can get a clean copy!



However, not ALL installations of Windows XP have ALL the system files cached into this folder! You may only have around 25-50MB of files in this folder under Windows XP depending on the settings in the registry.