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How to Repair Corrupt or Damaged Windows System Files with System File Checker
Sometimes one of the important Windows system files can get corrupted. Then you may get messages about missing DLL files or have other indications that there is a problem. This tip will discuss repairing the system with System File Checker (SFC).
This is one of the numerous command-line system tools that come on all current versions of Windows. It will scan all protected system files and replace incorrect or damaged versions with copies from a backup cache or from an installation disk or folder.
Malware infections are one source of this type of problem so make sure your system is clean before trying repairs. Also, System Restore is easier to use and should be tried first if possible.
Using System File Checker in Windows XP
1. Open a command prompt (or the Start-Run line).
2. Type and enter "sfc /scannow" (without quotes but with the space).
Your files will then be scanned and repaired if necessary. It may take 10 or 20 minutes, depending on your system.
Unfortunately, in Windows XP it is quite possible that SFC will first ask for your Windows installation disk. Most people only have a restore disk so it is necessary to take some rather involved steps before running SFC. Even if you have an installation disk, it probably won’t work unless Service Pack 3 is on it. A discussion of how to proceed if you have no proper installation disk is at this Bleeping Computer forum.
Using System File Checker in Windows Vista/7
The procedure generally goes much smoother in the newer versions of Windows.
1. Open a command prompt with administrator privileges.
2. Type and enter "sfc /scannow" (without quotes but with the space).
Your files will then be scanned and repaired if necessary. Again, it may take 10 or 20 minutes, depending on your system.
If your Windows Vista/7 system won’t boot, there is still a possible way to try a repair. In such cases, SFC can be run offline using the Windows Recovery Environment (RE). Again, the catch is that you need a setup disk. Details of using RE can be found at WinHelpOnline.
After running System File Checker
It is best to go to Windows Update after any repair is done to ensure that you have the latest file versions.
As an aside, my personal preference for dealing with corrupt files is regular backups. However, when helping other people (who didn't back up) SFC has its place and is part of the regular toolkit.
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This tips section is maintained by Vic Laurie. Vic runs a Windows blog called The PC Informant and also operates a computer education website.
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Comments
One of the best tips I can give for those having issues with permissions..is to simply turn off your UAC. See the only thing it is, is an hinderance and it causes more problems than you know.
If you have up to date internet security, then quite why you'd want to run this thing is beyond me.
The vast majority of people using windows 7 are using the 64 bit version of which ever install they use.
There is zero security issue...the UAC is there for stupid people...to inform them they are about to install software...that's it!
turn of UAC, then run sfc /scannow and you will be sorted..without any problems...the uac is the main cause of sfc not being able to repair.
Windows 7 x32 bit users still make up 15% of operating systems which is quite a lot. Gizmo's Freeware does not recommend to disable UAC at all. Microsoft built this code and it's prompts for good reason and it should be left alone.
I tried this method, it is gone very somoothly,BUT unfortunateky my free avast antivirus crashed. I dont know why??
I have the same issue - sfc /scannow on vista said it found corrupted files that it could not fix and that I could see details in cbs.log. However, when I try to look at cbs.log, it says "access denied". I have administrator access and ran sfc /scannow as administrator, and I tried accessing cbs.log using administrator command prompt but still got "access denied" message. Is this important enough to need to figure out and fix? How else can I find out which files are corrupted?
Sorry but we are unable to provide individual support here in the comments. Please post your question in our forum.
AN excellent tool that's simple to use and does all round repair of a Windows system-
http://www.tweaking.com/index.php?/content/page/system_information.html
I've also had the same problem for 6 months now sfc /scan now is easy.. but no were no knowledge does it say how to fix the dam errors.. you think people would say and not have to do a factory default re-install os which doesn't cure it either. its just plain stupid really... sick and tired of reading forum after forum .. they need to make a program that directly fixes the issues and such little cost or some proper FAQ's because it not getting anyone anywhere
I too have tried this and find that there is a corruption that it can't fix. I got this after it Verified my system. Windows Resource Protection found corrupt files but was unable to fix some of them Details are included in the CBS.log windir\logs\CBS\CBS.log.
I ran with admin rights and it wouldn't let me pull up the log file. System seems to work just fine. Not sure what could be corrupt. Did a fresh install less than a month ago.
I had this same issue with Windows 7 x32 after using a program called AppRemover to uninstall AVG9. I reported the flaw to the developers who quickly released an updated version but unfortunately this didn't help me.
From what I could tell, a new install of Windows was going to be the only way forward although I've since taken the easy way out and moved to Linux :)
Despite my comment above I highly recommend AppRemover as being the best specialist tool for removing security programs. Using the system uninstaller can leave remnants behind which will conflict with installations of new software, and using a third party uninstaller with more aggressive settings like Revo can remove shared components which other programs need to function.
http://www.appremover.com/
Any amount of updates/sp's over & above the first installation from the OS disc makes this effort "sfc /scannow" fruitless as Windows(XP)clearly states, the current operating system is newer than the one wanting to access/install from & I can't go any further.
As I say in the tip, you need a disk with the SP3 version. You might get some help from the reference Pilgrim mentions (http://www.updatexp.com/scannow-sfc.html)
XP users might find this of use:
http://www.updatexp.com/scannow-sfc.html
Ran sfc /scannow on vista. It said it found corrupted files that it could not fix and that I could see details in cbs.log. However, when I try to look at cbs.log, it says "access denied". I tried changing permission rules, but nothing. How can I look at the file and any idea how I can fix the corrupted files once I find out what they are? Thanks
finally got access to cbs.log, but it's greek to me. Seems some files were corrupted and they were unable to be repaired. Short of reinstalling windows, how can I fix the files?
As much as I would like to help, it is not possible for me to give detailed assistance with specific individual problems. Systems vary too much.
See this Microsoft link:
http://support.microsoft.com/kb/928228/en-us
Laurie, I select the sfc.exe rightclicking and choosing to execute with administrator priviliges. That's the way?
Willem
Open the command prompt as described here: http://www.techsupportalert.com/content/quick-ways-open-windows-vista7-c...
Then proceed as described for the present tip.
don't know what I did wrong or...worse...might have a real corruption in my system but, when I run sfc /scannow on my Windows 7 system the command window pops up for a fraction of a sec and closes. Don't have to wait 10 -20 minutes!
It also happens when I boot with F8 entering safe mode.
Willem
Are you running the command prompt elevated with administrator privileges? If not, it behaves just as you describe.
thank you Laurie,
googled a bit to really understand things and managed to get things working: opened cmd.exe with administrator privileges and typed in "sfc /scannow". Everything's scanning now fine.
Thanks!
The easiest way to use the System File Checker and Disc Check is to install the free Glary Utilities. It offers all the Windows inbuilt tools with one click.
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