Summary: The System File Checker is a little known utility that validates that Windows own files are undamaged. It's a 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.
Related:
-
How do I tell Windows where my I386 folder has moved? You can move the I386 folder, but in order to keep Windows File Protection happy, you'll need to update a registry key as well.
-
When I use Start-Run and type in a command, why does a window just flash and disappear? Start-Run, or the Run item on Windows Start menu is a way to run any program on your machine. Some will work as expected, but Start-Run of others just produces a quick flash. We'll look at why, and what to do instead.
-
I have no CD - how do I get at Windows XP setup? If you don't have your Windows installation CD there are still a few things you can do. If you have an image of your CD, you may be able to do more.
Article C1896 - February 28, 2004
Leo, I installed IE 8 on my XP mach. Didn't work. Removed it and IE 7 wouldn't work. Removed it IE 6 worked. Reinstalled IE7 and all fixes & SP3. Works fine. Outlook Express now has a prob. Cannot open any links from outlook. Ran SFC /scannow. Ran to completion no problems. OE still not working for links. Any ideas?
Posted by: Mike Passaretti at April 7, 2009 7:28 PMI am having problems controling iexplorer.exe How do i keep it from Crashing my computer. I'd like free safe download, I have Windows XP home Edition
Thank-you
Posted by: Diane at May 30, 2009 2:13 PMI have Windows XP. I do not have the file
SFC/scannow. Please explain.
14-Jun-2009
Posted by: CD at June 13, 2009 10:12 AM
I ran SFC /scannow. Window pops up saying - Please wait while Windows verifies that all files are intact and in their original version. When that got done, window went away. I didn't see anything happen after that, so I tried running SFC 'scannow again, and same window came on saying the same thing. What and how do you scan?
01-Aug-2009
Posted by: Richard Fuller at August 1, 2009 5:24 AM
i have vista and i'm pretty sure i have a virus i can't get rid of. i keep trying to open up SFC but it suddenly appears and disappears. what does that mean/what should i do?
18-Sep-2009
Posted by: matt at September 17, 2009 11:11 PM
Leo,
Posted by: Vaerio Ferreira at September 18, 2009 8:13 AMwhen running SFC \scannow, with the right XP SP3 CD in the CD-ROM drive, a window appears repeatly saying" Files that are required for windows to run properly must be copied tp the DLL Cache. Retry, More Information, Cancel". Answering "Retry" makes drive light to twickle and the progress bar to go up a little until this window strikes again.
"More Information" reports the following:"Possible reasons for this problem: 1.You may have inserted the wrong CD. (i.e., a different windows product CD than the version installed. 2. The CD-ROM drive in your system is nor functioning".
I confirmed that the CD is the right one and is updated to SP3 such as the version installed in the PC.
After hundreds of retries the process ends up apparently well i.e. without further infornation. Can you realize what's up?
I have only the original XP Home ED. CD. It is useless to run "SFC /scannow" because if I try & use it my system always says I have the wrong CD inserted.
So what is my option when I have upgraded to SP3, then installed multiple updates? I don't want to run a repair install. I tried this once before with another problem. It installed original files which clashed with the Windows Updates. My OS was totally hosed.
I want to obtain or reinstall the Search helper files which have suddenly gone missing. How do I get up to date ones ( or ones that are compatible with all the Win Updates?) using SFC?
Posted by: Brian Kochera at September 22, 2009 4:59 PMHi Leo! I have had a problem with two computers in my home that I am sure is related to one of the sites I visit. As I only access approximately 10-15 total sites and am the only user, a virus seems the only possibility. 98% of the time, when I power up my monitor times out like it is recieving no video input. I have run "sfc /scannow", but there have been no errors found. Since it has happened with both systems, I am sure I have a virus, but have no practical knowledge of what virus/virus(s) I may have, I have no idea how to proceed. Any suggestions?
Posted by: Aaron Minidis at October 16, 2009 9:29 PMRan SFC /scannow. Used original setup disk. Got a message that I needed setup disk 2. Hence this action did not solve my problem. I am going to the microsoft blog via an alternative browser. I remember seeing a wordperfect version of a fix to the problem.
Posted by: James Koontz at October 25, 2009 4:52 AMI don't have the servise pack 3 cd I downloded it from windows update. I have servise pack two what do I do Leo?
Posted by: Caleb at November 1, 2009 4:48 PM