Please read this:

The problem is the first fix (work around, actually) MS put out for the "Duqu" virus/Trojan.

If you installed the first one, go to http://support.microsoft.com/kb/2639417

and disable it. Then run your sfc /scannow. Offline. then re enable it. Bet that solves your problem. That's what happened to me.

You might have to roll back part of Security Update MS11-100 but don't do that until you try what I suggested re the duqu fix.

If after reversing MS's first Duqu fix you still can't run  sfc /scannow, research MS11-100 to find out if a 'duqu' fix was in there, or if it caused a denial of access to system files. If it did,  sfc  /scannow won't run. You can probably roll that one specific update back, but only do so when disconnected from the net. 

Research that possibilty here: http://technet.microsoft.com/en-us/security/bulletin/ms11-100

However, reinstall it after you finish. It's that important.

I've had the same quirk for a couple of months regarding sfc /scannow. Isn't this the same scan and repair as the chkdsk option on the HDD? The one that starts on a reboot.

CopperHill 

No. sfc /scannow deals with windows system files only and repairs any integrity violations.

chkdsk does only that.  chkdsk /f /r scans for sector as well as file integrity, indexing, etc. repairs errors and is a 5 part scan (if i remember correctly) takes one helluva long time as well.

Hi Doc I downloaded the 2 Fixit msi files but haven't run them yet.  I'll pull my wireless usb device out before doing that.  I was wondering though after I ran chkdsk last night does it create a report anywhere telling me what it found?

Yo, BDBF. I'm really sure the problem came from that fix.

The logs should be in your cbs logs.

Well I found it Notepad can't open it.  Access is denied.  So what's the next hoop I have to jump through.

did you "unfix" then run sfc /scannow?

Not yet I was trying to read the CBS log.  I had to copy it first and read the copy.  The original is locked.  It should stay that way.  It was useless for me to try and read it.

I'll try the fix now offline.

Sorry, double post.

Okay SFC /scannow ran and found some stuff to repair.  Nothing changed though in any visible way.  Ran the enable fixit went online and thanks at least I know now that to run SFC I will have to disable that access deny lock on the system font dll.

Good news. You're welcome, bud.

Worked here too. Thanks Doc!

I discovered another way to fix it that worked for me. I used the takecontrol.reg which I already had installed and took control of the system 32 folder. Now I can run sfc without issue.

JC, do you have the MS patch mentioned in #26 installed? 

Yes Doc but even after I disabled it I still could not run sfc. Would only verify to 7%. Once I took ownership of my system files I ran and completed sfc. It found some corrupt files to.

I ran the sfc /scannow to completion but the window vanished after it finished. How do I find out if it found anything.

Look in the log. (cbs file). Type "logs" w/o the quotes in the search box in your Start Menu.

They're in Java Script and Windows can't read it.

Use notepad to open Uvah.

c:\windows\logs\cbs\cbs.txt

copy that file to somewhere in My Documents and it will open in Notepad.

Gotcha .............

That file is longer than I am tall. Sheesh! Mostly what I got was a lot of files moved around. This damn thing moves so fast I was actually seeing entries made dozens of times a second! and that was just the repair end. The other part was ignoring ownership on system files, a lot of them. Beats the hell out of me what all that means.