The System File Checker program (sfc.exe) was introduced in Windows 98. You can use this program to scan your system files to locate those that have become corrupted in some way and replace them with other versions. This is also the easiest way that you can use to extract system files from the cabinet files on your install disk in order to restore the original version of selected files.
You can access the program in one of two ways. Either go to the Run option on the Start menu and type sfc or go into Programs then Accessories and from there to System Tools and select System Information. From there go into the Tools menu and select System File Checker.
The System File Checker has two options. The first option allows you to scan all of the system files in your windows installation looking for any that have been altered since their original installation. For any files that this option finds you are then given a choice of restoring the file (either from a backup copy or your installation disk), you can advise the system checker that the version found is correct and not to report this file in future scans, or you can ignore the file and continue the scan. It can be useful to run this option if your system is misbehaving and you suspect a corrupted system file but are not sure which it is.
Sometimes the error message that you get when trying to run one of your programs will report specific system files as being the wrong version for the software to run. Other times when you look up how to fix a particular error message the documentation will tell you of files that need restoring to a specific version in order to rectify the problem. Rather than having to figure out which cabinet file holds the file(s) that you are looking for and then extracting the file, you can use the second option of the System File Checker to do it for you. All you need to do is to specify (one at a time) the file(s) that you want to recover and select from the options list that appears as to where you want to restore the file from. The file will then automatically be extracted from the appropriate cabinet (.cab) file and restored to the correct location within your system folders.
This article written by Stephen Chapman, Felgall Pty Ltd.