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What is the System File Checker, and how do I run it?

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Summary: The System File Checker is a little known utility that validates that Windows own files are undamaged. It's simple to run command line program.

What is the System File Checker, and how do I run it?

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.

Enter the SFC, the System File Checker.

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 or a location with an image thereof. (See this prior article about not having an installation CD on some of the alternatives if that's the case.)

To run the system file checker press Start, Run, and then type in SFC followed by its options.

The most common usage of SFC is this:

SFC /scannow

This causes SFC to scan your system immediately. SFC can take a few minutes to run. As I said above have your installation CD or equivalent available in case SFC needs to replace a damaged file.

While it's not documented anywhere, if SFC replaces any system files I'd reboot. I just like to make absolutely certain that the file replacement actually takes effect.

The Microsoft knowledgebase includes more detailed SFC documentation including more options to check at boot time, control the size of the system file protection cache, and so on. Speaking of which, the knowledgebase also includes System File Protection documentation covering the mechanism Windows XP uses to keep your system files safe automatically.

UPDATE: If you have no CD, but you do have an I386 directory or CD image somewhere, check out this article: How do I tell Windows where my I386 folder has moved? Once you make the changes therein, you should be able to run SFC to completion.

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Article 154 | Posted February 28, 2004

Recent Comments

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I'm not totally sure I understand your question, but:

- you can run SFC /SCANNOW from the Start->Run menu item

- you can run SFC /SCANNOW from within a command prompt

You might try safemode, and you might try the recovery
console as well, if things aren't working for you.

ALSO, I'm not 100% convinced that SFC will restore NTLDR. I
could be wrong.

Leo


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Posted by: Leo at June 3, 2008 10:25 AM


Hi Leo--some good tips above -but still stuck.
OE will not open properly as it says it is already running. Then on trying to close windows it says it IS running but programme not responding so "close programm" required to shut down.

Thus far I have --closed -rebooted--gone back to restore point- started using Thunderbirds fine --but left with the inability to get rid of OE running -cant uninstall either as access denied.
Have installed IE 7 too-hoping it would re-intall OE properly. NOPE -as you inferred .

Bother--

Tried SFC /scannow too-

Any ideas?
Thanks Dick

Posted by: DR DICK DAVIES at June 19, 2008 02:51 PM

i have toalt rewind my comp itts hard cause i cant get my usb deivice working and im 12 and
i like fixed loads of computers cause like
i am 12 and female i no how computers work but i need help because i may be very intelagent buh
i just cant get my usb working can eny one help me

Posted by: mazdapan at June 22, 2008 12:53 PM

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Well, to start with there's not enough information here to
help you with your USB problem.

But if you want people to take your requests for help, I
*strongly* recommend learning to spell and write English
better, OK?

Leo


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Posted by: Leo at June 23, 2008 08:29 PM

Leo, I suddenly started being unable to use the photo album on my photoshop elements. It stops while trying to open the program and gives an error message of DirectX installed but can't be initialized please reboot computer and try again. I rebooted without resolution, I ran adware/spyware, virus scans, I tried to redownload DirectX 9.0c, I took off my photoshop and put it back on my drive, I got software that was supposed to help with directory file problems without help. I tried the SFC /scannow but as someone else noted above it requested my CD which is SP1 but then said it wouldn't work because I have SP3 running. Sorry this is so long. Any suggestions?

Thanks,
Jeff

Posted by: Jeff Anderson at July 8, 2008 10:36 PM

Hey I just wanted to let you know that I too had this black screen and figured I was toast. I thought I had a bug or something and was going to take my comp to a local shop to get it fixed but you helped me out. Who knew that "explorer" did so much and the system scan helped a bunch to figure out why my computer wasn't running the computer at start up. Thanks Leo!

Aaro

Posted by: Aaron Racimora at July 10, 2008 08:15 PM

I m sitting in an Webworld and here i m surfing but the problem is that here acess is denied for everything just u have to do is just surf and go so i want acess to everything for installation,usb,etc...

Posted by: ankit at July 19, 2008 06:20 AM

hi
I have an installation CD but not a SP3 CD which I am asked to use when running SFC /scannow. What to do?
tanx

Posted by: mostafa at July 24, 2008 07:44 AM

NTLDR missing or boot.ini has been changed:

Use Window XP CD-ROM, run the Recovery Console
and run the Bootcfg/rebuild.

Posted by: Ren at July 30, 2008 11:18 AM

I have read your article very intresting. I got a virus in my computer and it changed the desktop settings and then wouldnt let me change them back i eventual got the desktop settings back after reading a few articles and now thew internet explore i find won't show as ie 7 but it is when i log onto hotmail live it say something like to get the best out of this service you need to upgrade or be running ie 5 or later which i am but for some reason it wont recongnise this.

any help greatly appricated

richard

Posted by: RIck at August 3, 2008 06:05 AM

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