Helping people with computers... one answer at a time.

Defrag organizes the data on your disk for faster and more optimal access. If it crashes it's probably a problem with the disk's data.

I am unable to defragment my computer. I used to be able to do this but some 6 months or so ago, I noticed I could no longer do so. I could start the process but every time I got to around 10% defragged the computer would reboot. Sounds silly I know but I run XP on a Celeron 26000 and have tried everything I know to fix, short of re-installing. I am at a loss. Could you please shed some light on my problem? Have you come across this before?

I do have some ideas, yes. My guess is that there's something wrong with the data on your hard disk or the disk itself. The good news is that in all likelihood we should be able to repair it.

I would guess that the most common cause of the defragmenting software crashing is a "logical" problem on the disk. By "logical" I mean a corruption of the data on the disk, like the directory entries or the disks lists of areas that aren't in use.

My first step would be to run CHKDSK. Specifically, "CHKDSK /F".

Fire up a Windows Command Prompt (usually in Start, All Programs, Accessories, and type in CHKDSK C: /f (I'm assuming C: is the drive you want to defragment). It'll probably ask if you want to schedule the CHKDSK for the next time you reboot, to which you would say yes:

CHKDSK command asking if it should run the operation on reboot

Reboot your machine, and allow CHKDSK to run to completion. Once your machine has completed booting back into Windows, try to defragment again.

"My first step would be to run CHKDSK."

If it still fails, I would next re-run the CHDSK command, this time using the "/R" switch (CHKDSK C: /R). This should perform a more thorough scan of your hard disk looking for errors and repairing them if it can.

If it still failed, I would next run the System File Checker to make sure that the files that comprise Windows itself are intact. Since the disk defragmenter is a part of Windows, if some component of this tool has been corrupted, this should repair it.

Finally, if things are still failing, then I'd seriously consider a hard disk repair and recovery tool such as SpinRite. It's not free, but it has a stellar record of repairing hard disks that have or are on the verge of failing. Since I believe that the disk defragmenter is most likely crashing because of problems with the disk, a run of SpinRite, followed by another run of CHKDSK, would be close to my last best guess at repairing this situation.

Article C3031 - May 20, 2007 « »

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

May 25, 2007 7:18 PM

I had the same problem when I was using Windows ME. Defrag would go to only 10% and bounce back to zero and start over. Again at 10%, back to zero again. I don't remember who, but some computer tech. like yourself told me that the programs running in the background were part, if not all of my problem. He said to turn off everything I could and try again. It worked fine and everytime after I would automatically turn things off and had no more problems. I don't know if it is any help but it worked for me.

May 25, 2007 7:35 PM

Doesn't "defrag" require a certain amount of free space to run...possibly that could be the problem? Altho I guess you'd get an error for that, I'm not sure. Just a suggestion.

May 25, 2007 9:35 PM

After turning off everything that comes on automatically or timered, screensaver was the ultimate culprit.

Ken Power
May 27, 2007 4:32 PM

I had a somewhat similar problem some time ago, and it turned out to be something as simple as a screensaver or other software configured to activate automatically.
It was too far back for me to remember details, but ensuring that nothing could activate the drive whist defrag was functioning did stop it from continually restarting before completion, and occasionally crashing.
It also helped when I installed "Diskeeper", which takes care of defrag automatically, and works so much faster than the built in MS service.

May 29, 2007 10:22 AM

Sometimes that reboot at the 10% level is because of something running in the background -- anti virus, etc. Boot into Safe Mode and then run the defrag program. It should run just fine then.

chris cafferata
May 30, 2007 7:28 AM

Had the same issues some time ago. I suggest running defrag in 'safe mode' or, as was my cure, disable the antivrus software. Thanks.

May 30, 2007 11:07 PM

My system started shutting down when running defrag (no reboot). Later it shut down when Spybot was running. I checked out the CPU Usage via the Task Manager and found Spybot was utilizing the CPU at 100%. Checked out Defrag and found a similar situation. Hmm, I built this computer about 2 years ago and haven't cleaned it up. When I opened it up it was cruddy. I cleaned it up and restarted the system and no shutdown problems anymore.

Hope this helps and causes others to clean up their computers.

September 13, 2007 8:49 AM

The defrag on my computer crashed on my machine several months ago and would also reboot after a few minutes. After reading your article and trying the "chkdsk c: /r" command my computer was totally cured of its ailments. Thank you Leo for your comprehensive help.

December 18, 2007 11:11 AM

I have a similar problem my comp is basically a gaming comp with duel core and dual graphics cards, after i had to repartition due to a error checking crash the defrag would start get to 25% then just crash suddenly

April 9, 2010 4:15 AM

My computer crashes during attempts to full virus scan (MSE) or defrag (MS) or CHKDSK C: /f. Please help!

Current system:
Microsoft Windows XP
Home Edition
Version 2002
Service Pack 3

Fujitsu Siemens Computers
Intel(R) Core(TM)2 CPU
T7200 @ 2.00 GB of RAM

Current disk defragmenter info:
C: NTFS 112 capacity Free space 47 GB Free space 43%
(Was only 15% free space at very start of problems, before I deleted or reduced old files)

Originally Norton 2006, now uninstalled and replaced with current Microsoft Security Essentials

Browser: firefox version 3.5.9 (Have IE too but don't use)

The story so far:

I came back from a long holiday and turned my computer on. It soon wanted me to update to the latest Firefox (must have been 3.6?). It may have also updated my windows automatically. Then every time the standby/hibernation/screensaver came on (not sure which was the culprit), the computer would crash- I would just get a grey screen when I tried to get back on by moving the mouse.

I restored the system to a few saved points back from before I had agreed to install the new firefox. I also stopped the computer going onto standby or hibernating. I couldn't work out how to turn the screensaver off. The standby/hibernation/screensaver stopped crashing the computer after this, and I was careful not to upgrade to firefox 3.6 again just in case, staying with the version I was on but still accepting upgrades (now on 3.5.9). I have still been accepting the automatic windows upgrades though, because I was told I should do so.

So, I now had a more useable computer. I tried to virus check but the virus check (Norton 2006) would crash every time I tried to do a full check. I analysed in the MS defrag tool that came with my computer and saw that I only had 15% space free, so I tried to defrag. The defrag also crashed each time, usually at 3%.

26th January:
-defrag crashed on A0044502.rbf
-(I noticed the name was similar to the one the virus check crashed on before)
-defrag then crashed on another of a different file type but I didn't note it down (tmp.edb?)
-defrag crashed on C:/system volume information/_RESTO~1/RP320/A0045026.rbf (I think virus check then crashed on this one too)
-virus scan crashed on A0045030.rbf

I did run cmd chkdsk_/f as told to by a friend. Did it 3 times and screen went too quickly to see what writing said before it booted up.

-defragged again, it crashed on A0045107.rbf

I then had to finish some work urgently, so did not come back to trying to fix this problem for weeks. I just didn't let the antivirus scan and didn't try to defrag, so had no crashes. When I had time spare, I went through removing unnecessary programs, deleting unnecessary old work files and reducing large graphics work to smaller sizes. By the time I had finished my urgent work and could return to the problem, I had 43% space free.

Wed 8th April:
-I uninstalled Norton 2006 and then installed Microsoft Security Essentials (and turned on windows firewall with no exceptions) to see if this would pick up any viruses. Quickscan revealed none. Full scan crashed each time unfortunately.
9th April:
-CHKDSK C: /f either crashed or was working incredibly slow (1/2 hour on same file) both times I tried to do it. Both times it crashed on 66% of verifying file data (4 of 5)
-SFC typed in run: the black box flashes up but then disappears so fast you can hardly see it. Nothing else happens. I tried a few times.
-I rebooted the computer into 'safemode with command prompt' and tried SFC /SCANNOW, and got the following error:
"Windows File Protection could not initiate a scan of protected system files
The specific error code is 0x000006ba [The RPC server is unavailable]."
-I rebooted in 'safe mode' and typed SFC in run. Same thing happened as happened before in regular windows.
-I rebooted in 'safe mode' and tried a full MSE virus scan. After an hour of working, it crashed on this file: C:/System Volume Information/_restore{5C5FC002-5FB5-4560-96DA-E32D8569FB2E}/RP320/A0045038.rbf. The full virus check was almost finished, guessing 80% done in the green bar.
-I tried to defrag in 'safe mode', which soon crashed on C:...A0070595.MSI
--I opened C: in windows, then virus checked all the files in it with MSE in 4 or 5 batches, and MSE thought they were clean. Does this mean it's probably not a virus?
-full virus scan in safe mode- it crashed on exactly the same file as before- C:/System Volume Information/_restore{5C5FC002-5FB5-4560-96DA-E32D8569FB2E}/RP320/A0045038.rbf.
All these April crashes just involved the screen appearing to freeze because the virus check or defrag was not moving on from the file it said it was on... then when I'd try to stop it, the screen would freeze completely so I would have to manually shut down.

Please help me resolve this problem! Should I be backing up my work immediately? If I back it up and there's a virus, then my external hard drive backup could become infected. But if I don't back up, I could lose a lot of work.

June 6, 2010 8:54 AM

Hi, I'm hoping someone can help me....

Even though defrags never crash anything on my machine DSKCHK always crashes after it finishes (through rebooting) lately.

I start CHKDSK using the /f parameter, it tells me that the drive is currently in use (locked) and it will have to start on restart, I type "yes", I restart and it runs after the Windows logo appears. When it finishes it crashes with a generic type BSOD with only 0's in its code, and NO title.

I'm on Windows XP SP2
Compaq (he's and old one)
Intel(R) Celeron CPU
564MHz @ 512MB of RAM

This ever happen to anyone? Please, it's making me go crazy!!

Very Annoyed
November 17, 2010 5:32 PM

Just went through something like this.

Put the drive on a different machine (not as the boot drive) and told MalwareBytes' Anti-Malware to scan it. Lots of nasty files (with similar names) got deleted. Put the drive back on the main system, things seem to be ok now.

Jeffrey Kastin
October 15, 2011 8:13 AM

Why not use Chkdsk via windows explorer. As per:

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