Using Windows System File Checker

System File Checker, or SFC, is one of the best features of Windows, and also one of the least used. And that’s too bad. Many computer problems can be solved by running it, and yet very few people ever use it. The System File Checker utility (SFC), has been available since Windows 98. It’s used to scan for missing, altered or corrupted system files and to extract the original (correct) file and replace or repair damaged files.

Probably one of the reasons why SFC isn’t more widely used is because it’s not a simple point-and-click program. It requires users to run it from DOS-like window and to enter commands and use switches. But before you decide to skip this tip right here – with the talk of DOS boxes and commands and switches – don’t skip this tip. At least 50% of you could benefit from this tip. So, hunker down, and we’ll make it as simple as possible.

There are only slight differences in these instructions for different versions of Windows. In Windows XP you can run this without opening the Command window with administrator rights, while Vista and Windows 7 users will need to open the Command window as an administrator. While you may be the only person who ever uses your computer, on Vista and Windows 7, you’re not, by default, an Administrator. Somewhere in Microsoft’s big brain, they’ve decided Windows is safer if users aren’t administrators by default. This must have occurred to them after Windows XP came out. But that’s a discussion we could have another day.

If you’re using Windows XP please note: Before you start System File Checker, make sure you have your Windows installation disk inserted in your CD/DVD drive. If you want to repair or replace missing, altered or damaged files, that’s where Windows is going to get them. If you’re one of those who don’t have a Windows installation CD, the restore disk that came with your computer may work.

Plan on at least 30 minutes to run System File Checker. It may not take it that long to run, but plan on 30 minutes just in case. Whether or not SFC tells you to, you should reboot after you’ve run System File Checker (if it has repaired or replaced any files).

OK. To run System File Checker (hereinafter known as SFC because I’m tired of typing System File Checker) do this:

Windows XP users – Press the Windows Key + the “R” key. In the Run command line type CMD and press enter.

Windows Vista and Windows 7 users: Type CMD in the start menu search and when cmd.exe appears at the top of the start menu, right-click on it and select “Run as administrator”. This is important. If you don’t do this, you won’t be able to do anything at all..

OK. Now that you’re all sitting there with a big black box on your screen (we hope), you need to type in some commands. DOS stuff is not very forgiving, so you have to type these commands exactly – and spaces are important too.

To run SFC so that it scans and replaces/repairs altered, missing, or damaged Windows System Files, type the following at the cursor:

SFC /SCANNOW

(Note: there is a space between SFC and the backslash, see it? Good. Don’t forget that space!)

Here are some other commands and switches you can use with SFC:

SFC /VERIFYONLY

The SFC /VERIFYONLY command scans the integrity of all protected system files but doesn’t repair or replace any damaged, missing, or altered files.

SFC /SCANFILE

The SFC /SCANFILE command allows you to check the integrity of a single file. For instance:

SFC /SCANFILE=c:\windows\system32\kernel32.dll

There are other SFC commands and switches you can use, but for us and most of you, the only command you’ll need to use is:

SFC /SCANNOW