I am pulling in old messages from my prior blog because I thought some of them had good insight.
Windows XP has the ability to protect itself from system instability caused by 3rd party software overwriting important system files, this built in functionality is called “Windows File Protection.”
By default, Windows File Protection is enabled and allows Windows digitally signed files to replace existing files safely. Currently, signed files are distributed through:
- Windows Service Packs
- Hotfix distributions
- Operating system upgrades
- Windows Update
- Windows Device Manager
If you or a program installer introduces a file replacement in any other way, Windows File protection will warn you of such changes and ask you to insert the proper CD to fix the issue at hand.
An important part of Windows File Protection is the command line utility:
System File Checker (sfc.exe)
The main reason for using this utility is when you suspect there may be a problem with a Windows XP system file. (See quote below for situations)
Perhaps you get a dialog box appear informing you of a problem with a .DLL file, or your computer may also be getting a dialogue box from SYSTEM\NTAUTHORITY and that it will shutdown in a minute. (To abort the shutdown, navigate to Start > Run… and type “cmd” -without quotes-. Within the new Command Prompt Window, type “shutdown -a” -without quotes- This should then abort the shutdown at hand.)
To run the System File Checker, simply navigate to Start > Run… and type in:
sfc /scannow
This command will immediately initiate the Windows File Protection service to scan all protected files and verify their integrity. If any erroneous files are found they will be replaced with the correct versions from the CD and Microsoft Update Cache.