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Q: stupid dumb "FAT32 disk checking"! ( Answered 5 out of 5 stars,   2 Comments )
Subject: stupid dumb "FAT32 disk checking"!
Category: Computers > Operating Systems
Asked by: gnossie-ga
List Price: $23.00
Posted: 27 Aug 2005 04:56 PDT
Expires: 26 Sep 2005 04:56 PDT
Question ID: 561083

Every time I boot up my computer (A Compaq running on Windows XP),
I've been getting this blue screen:  "one of your disks needs to be
checked for consistency."  The file system on G is FAT 32, etc.

I'm sure you know what I mean.  In this particular case we're talking
about a portable HD of mp3's, and if I disconnect it before firing up
my tower the blue screen won't appear.

Now, this is not the first time this has happened.  Not by a long shot.

I have a number of external HD's attached via USB cables to my
computer, and once in a while (these days more frequently, it seems) I
keep getting this stupid error message.  Why?

At first I thought there was a "disc error" or serious physical flaw
with my beloved portable hardrives, until I realized that, over the
last couple of years or so, I have been receiving this message about
maybe 4 or 5 different hard drives.  I have been out of horror
replacing them, but now I'm starting to think that the ones I've
mothballed in fact have nothing wrong with them!

Anyhow, it goes ahead and "checks the disks for consistency" and
NOTHING EVER HAPPENS!  Nothing is ever wrong!

interesting points:

Oddly, I'm not exactly asking you to solve my problem, since I'm not
sure there IS a problem.  I just don't want to be bothered with this

So your task is variegated:

1.  Explain for once and all, for the benefit of posterity, what the
hell is going on.

2.  Is there a way I can set Windows or the Bios to just never run
this check or show me the dumb blue screen?  Since there's never
anything wrong, I'd just like to be left in peace.  Plus I'm not
convinced that when Windows "makes corrections" they were even

3.  Also:  what COULD be wrong?  In other words, what could have
happened and what does Windows think it's doing?  Do hard drives
suddenly acquire physical scratches when the computer's shut down,
kind of like evil key gnomes?

4.  Is there a chance that some miswire in my mother board in fact IS
AFTER A TIME in fact causing FAT errors in my various harddrives?  I
have this nightmarish fear that every portable HD I plug into my
computer eventually gets ruined not because of any inherent flaw but
merely because it was plugged into my computer.

This is partially buttressed by horror anecdotes from work: 
colleagues telling me that when you get that "blue screen," it's going
to be only a matter of time before you'll have to physically replace
your entire hard drive.

Anyhow, somebody please set the record straight.  I know it's a minor
annoyance, but this is something that has bothered me and my
colleagues for YEARS now, and we need some reliable information.
Subject: Re: stupid dumb "FAT32 disk checking"!
Answered By: sublime1-ga on 27 Aug 2005 13:53 PDT
Rated:5 out of 5 stars

I don't think you have cause for great concern here.
Ever since Windows 98, Microsoft built into Windows
a safeguard to minimize disk errors by running Scandisk
after an imperfect shutdown, which is any shutdown that
doesn't allow Windows to go through the process of
ending all programs in a courteous way.

XP no longer has Scandisk. It's been replaced with 
CheckDisk or chkdsk.exe and serves the same function
of checking a disk for errors. It's good to run this
from time to time, followed by defrag, to limit disk
errors and consolidate the files on your drive.

If you just turn off the power to your PC instead of
going through a formal Shut Down, you will always get
this message, and this process will always run. That
kind of shutdown can, indeed, cause physical damage
to the disk surface, and result in errors in files
and the folder structure, potentially resulting in
corrupted, unusable files, and problems running the
associated programs. This is why it's best not to run
your computer during a thunderstorm, since a sudden
loss of power has the same effect as just hitting the
off switch on your computer.

As for blue screens implying eminent disk death, 
this is not necessarily the case. Windows throws up
blue screens for any number of reasons besides problems
with the disk drive, which have no implications for the
health of your hard drive.

Likewise, this error has nothing to do with the wiring
of your motherboard, and everything to do with Windows.


If you're shutting down your computer in the recommended
way, and you're still getting this message incessantly,
it can also be due to the fact that XP normally runs on
an NTFS file system, and you're using a removable drive
with a FAT32 file system. This can trigger Windows into
thinking there might be a problem, as noted in this 
article by John Savill on WindowsITpro:

"When NT boots it performs a check on all volumes to see
 if the dirty bit is set, and if it is, a full chkdsk /f
 is run. To stop NT performing this dirty bit check you
 can exclude certain drives. The reason you may want to
 do this is for some type of removable drive, e.g. Iomega

- Run the Registry Editor (Regedt32.exe). You MUST use
  Regedt32.exe and not Regedit.exe 
- Goto HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\
  Session Manager 
- Change the BootExecute value from:
  autocheck autochk *
  autocheck autochk /k:x *

"Where x is the drive letter, e.g. if you wanted to stop the
 check on drive f: you would type autocheck autochk /k:f *."

More on the page:

Here's a discussion of the "dirty bit" from Microsoft's XP
documentation (see Monty Python's Flying Circus for a thorough
discussion of "naughty bits"):

"If a volume's dirty bit is set, this indicates that the
 file system may be in an inconsistent state. The dirty
 bit can be set because the volume is online and has
 outstanding changes, because changes were made to the
 volume and the computer shutdown before the changes were
 committed to disk, or because corruption was detected on
 the volume. If the dirty bit is set when the computer
 restarts, chkdsk runs to verify the consistency of the

"Every time Windows XP starts, Autochk.exe is called by
 the Kernel to scan all volumes to check if the volume
 dirty bit is set. If the dirty bit is set, autochk
 performs an immediate chkdsk /f on that volume. Chkdsk /f
 verifies file system integrity and attempts to fix any
 problems with the volume."

In your case, the dirty bit may be being set simply
because it is a removable drive, and it isn't registering
with Windows as easily as an internal drive, since it's
not consistently available in that you are plugging it
in and unplugging it when it suits you. Imagine!

There are some other possibilities as to why chkdsk might run
all the time, but I think your situation is due to the removable
drive and the dirty bit. Nonetheless, I'll mention them here:

'Chkdsk Runs Each Time That You Start Your Computer',
due to:
- Hewlett Packard ScanJet 5100c Scanner 
- Damaged Registry Hives 
A Microsoft Knowledge Base Article:;en-us;316506

'Chkdsk.exe or Autochk.exe starts when you try to shut down or
 restart your computer'
Another Microsoft Knowledge Base Article:;en-us;831426

I hope that clears up the mystery, and resolves your
frustration with this issue. If anything's not clear
or a link fails you, just let me know.

Please do not rate this answer until you are satisfied that  
the answer cannot be improved upon by way of a dialog  
established through the "Request for Clarification" process. 


Additional information may be found from an exploration of
the links resulting from the Google searches outlined below.

Searches done, via Google:

"check * disk for consistency"

autocheck autochk *

"dirty bit"
gnossie-ga rated this answer:5 out of 5 stars
Great answer.  Thanks.

Subject: Re: stupid dumb "FAT32 disk checking"!
From: dmrmv-ga on 29 Aug 2005 09:37 PDT
A good and thorough answer, but:

"If you just turn off the power to your PC instead of
going through a formal Shut Down, you will always get
this message, and this process will always run. That
kind of shutdown can, indeed, cause physical damage
to the disk surface..."

As you point out, this can cause file corruption but hard drives
haven't been prone to physical damage from power-off for years now.
Subject: Re: stupid dumb "FAT32 disk checking"!
From: sublime1-ga on 29 Aug 2005 09:54 PDT

In my experience, shutdowns from the power switch have
been associated with an immediate and seemingly related
increase in sectors being marked "bad" and unusable by
a thorough chkdsk scan. If this isn't due to physical
damage, the outcome is certainly equivalent, to me.

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