How do i repair fdc.sys file that is damaged?

June 25, 2011 at 10:38:48
Specs: Windows XP
How do I repair a fdc.sys file within windows xp that is causing blue screen?! My PC crashed shortly after Firefox crashed. I was watching a streaming video for a local news channel when this happened.(it should be noted that Firefox was also trying to update to the most recent 5.0 version at that moment) I can boot to safe mode, but it won't let me access and spyware,anti-virus, or ckdisk without going back to blue screen again...

(also tried using commands in the dos prompt with no luck)

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June 25, 2011 at 12:14:08
sfc.exe /scannow maybe

1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.

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June 25, 2011 at 14:24:55
Worth a shot, thanx!

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June 25, 2011 at 21:14:29
"I can boot to safe mode,"

You can't run sfc/ scannow in Safe mode.

Your problem may NOT have been caused by a corrupt fdc.sys file.
Sometimes Windows can't tell you what is actually wrong and names a file affected by the problem instead.

Sometimes the named file HAS been corrupted because your hard drive is failing.

sfc /scannow can fix your problem, if Windows is working well enough to run it in Windows,and if the SP updates version integrated into the source it is checking against and the SP updates version installed in Windows is the same updates

Assuming the file IS corrupted and replacing it will fix your problem....

If you do not have a brand name system, or if you do but the original software installation is not intact...

sfc/ scannow is only useful if the Windows CD has the same SP updates installed in it that Windows has.
E.g. if XP has SP3 updates installed in it, the CD must have SP3 updates integrated into it.

If the SP updates version is different, SFC will NOT accept the CD as a valid source of files.

If you DO have a brand name system, usually the \I386 folder normally found on the Windows CD has been installed on the hard drive such that Windows knows it's there. SFC can use that as a source of files instead of a Windows CD.
The files in the folder are not updated, as far as I know, when you install newer SP updates in Windows.

I suspect that If the SP updates version integrated into the \I386 folder is different, SFC will NOT accept the folder as a valid source of files.

You can't easily stop SFC from running once you have started SFC / scannow.

If it won't accept the source as a valid source of files.....

Press the ALT-CTRL-DEL keys at the same time to pop up Task Manager
Press the Alt-U keys at the same time, then U to Turn off (Shut Down) Windows, or R to Restart Windows.

If your Windows did not have SP3 updates installed originally, there are two what are supposed to be identical copies of fdc.sys
- the one Windows uses in C:\Windows\System32\drivers
- and one in C:\Windows\ ServicePackFiles\i386

If Windows is working well enough,you can copy it from C:\Windows\ ServicePackFiles\i386
to C:\Windows\System32\drivers in Windows.

If you can't get into Windows,or if you can but it isn't working well enough....

You need a Windows XP CD, or an XP Reinstallation CD that came with the brand name computer. It probablly doesn't matter whether it's Home, or Pro
Boot the computer with the CD and let the initial files load.
At the first screen at the end of that, press R to load the Recovery Console .

Type the number before the Windows installation it finds, press Enter.

Usually that's 1, press Enter.

(Note - If the Recovery Console finds NO Windows installation, you have a SATA hard drive and the bios Setaup has the SATA controllers in SATA or AHCI mode.The XP CD has no built in SATA controller drivers, and because of that by default cannot recognize SATA drives when the SATA controllers are in that mode, unless you load the drivers by pressing F6 at the beginning of loading files from the CD and have them on a floppy disk in a conventional floppy drive.
If you change the mode the SATA controllers are running in in the bios Setup to an IDE compatible mode, the Windows CD will then recognize the SATA drive(s),as (an) IDE compatible drive(s), and the Recovery Console will then find a Windows installation. If you have a brand name system, we probably can't find the info to tell you what you need to change specifically, but whatever it is, it's set to SATA or AHCI or similar, it's changable, and at least one other choice is an IDE compatible mode of some sort.)

You then see.....Password:

Usually there is no password - just press Enter.

Type.... copy C:\Windows\ServicePackFiles\fdc.sys C:\Windows\System32\drivers\
, press Enter.

If you are asked whether you want to replace fdc.sys, answer yes.

Type.. exit (press Enter)
to close the Recovery Console and restart the computer.

Don't press a key to boot from the CD .
See if Windows loads normally.

NOTE - some brand name computers come with the ability installed to access the Recovery Console while booting without needing the CD -you see the choice while booting

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June 25, 2011 at 23:20:07
Thanks Tubesandwires, Followed your advice closely. The tower is self-built, not brand name. And I'm using Windows XP Professional which includes SP3 on disk. Got all the way to the end and received a message saying the file can not be found. So I Imagine that the file is either missing or misplaced?
Any thoughts from here?

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June 26, 2011 at 07:27:02

I made a mistake.
The second identical copy of fdc.sys on my XP MCE 2005 installation, which has SP2 updates built into the first of two CDs and has been updated in Windows with SP3 updates, is in

so to correct the line, if you had / have that situation too....

copy C:\Windows\ServicePackFiles\i386\fdc.sys C:\Windows\System32\drivers\
copy C:\Windows\ServicePackFiles\i386\fdc.sys C:\Windows\System32\drivers

(on that computer fdc.sys in C:\Windows\System32\drivers and in C:\Windows\ServicePackFiles\i386 is the one included in the SP3 updates)

If SP3 updates are built into the XP Pro CD, you may not have a second identical copy of fdc.sys on the hard drive.

You could search C:\Windows (and subfolders, the default) for fdc.sys to see if you DO have an identical copy somewhere - same date and size as in C:\Windows\System32\drivers (unless it's damaged such that that's not correct), and modify that copy command line if you need to, if you do.

Mine is 27kb (rounded) in the search results, more specifically, RIGHT click on it, in it's Properties, 26.7kb, 27,392 bytes.
The date in the search results is the same as the Modified date in the Properties.
On two different installations, it's April 14 2008 on the MCE 2005 computer, April 13 2008 on an OEM XP Pro SP2 installation that has been updated with SP3 updates.

(Both those installations were installed from CDs that had SP2 updates originally. It doesn't matter if your date is different - it may be newer if it was built into the CD - but the size should probably be the same if your installation has SP3 updates installed.)

It's the driver for the floppy disk controller, by the way.

If you don't have an identical copy, or in any case, you could.try this.......

Boot into Safe mode.

Start - Run - type... cmd

Insert your XP CD in a drive.
Close the window if it auto starts.

Type.... extrac32 (CD drive drive letter):\i386\fdc.sy_ C:\Windows\System32\drivers (press Enter)

E.g. if the CD or DVD drive you have the CD in is E, type....

extrac32 E:\i386\fdc.sy_ C:\Windows\System32\drivers

You will be asked if you want to overwrite C:\Windows\System32\drivers\fdc.sys

Answer Y.

(I tried that - you are allowed to overwrite the file because it's not being used by the system, unless you're using the floppy drive at the time).

You MAY need to Restart the computer after that to have your error go away.

extrac32 is XP's cab extraction utility
fdc.sy_ is the compressed version of fdc.sys on the CD

OEM XP MCE 2005 is OEM XP Pro SP2, with a few Pro features that most people don't use omitted, plus the major Media Center group of programs and additional multimedia support.

All versions of XP MCE are OEM.
I have the Microsoft OEM MCE 2005 2 CD set.

If replacing fdc.sys doesn't get rid of the error, it may be there is something else wrong but Windows can't tell you what that is directly.

You could test your hard drive, that Windows was installed on if you have more than one, to make sure your hard drive is not failing.
(If it is failing that is probably what caused your problem.)

Check your hard drive with the manufacturer's diagnostics.
See the latter part of response 1 in this:

If you don't have a floppy drive, you can get a CD image diagnostic utility from most hard drive manufacturer's web sites, but obviously you would need to make a burned CD, preferably a CD-R for best compatibility, on another computer if you need to.


Seagate's Seatools will test any brand of hard drive.
Do the long test.

The bootable Dos versions of SeaTools can be used even if Windows is not working properly.

If the hard drive itself tests okay, any data problems found can be fixed, one way or another.

It's also possible, but not likely, that malware has made a bogus fdc.sys file and placed it in C:\Windows\System32\drivers.

If fdc.sys is in C:\Windows\System32 other than in C:\Windows\System32\drivers, that probably IS malware .

It would probably NOT be, in it's Properties, 26.7kb, 27,392 bytes.

Your problem could also be caused by corruption that CHKDSK (Check Disk) can fix.

You could Run: cmd
in Safe mode

(answer Y to the question)

that will test the whole partition with more tests than CHKDSK /F C:
does, including the free space

However, when you're checking the partition Windows was installed on, CHKDSK /R (or CHKDSK /F ) has to run just before Windows loads normally, and that may NOT work when Windows won't load normally or is producing an error, so you may NOT be able to do that until Windows will load normally.
OR - you can always run CHKDSK /R C: in the Recovery Console interface when you boot from the CD (there is no CHKDSK /F available there.)

I'm assuming your Windows installation has the C drive letter.
It's possible with XP (and 2000) that it hasn't been assigned C, depending on whether or not Setup detected other partitions on a hard drive that had already been assigned drive letters when it was run, which other devices have been or assigned drive letters or are assigned drive letters by Setup, and where and how the hard drive Windows was installed on is connected to the mboard when Setup was run.

E.g. I just re-installed OEM XP Pro on a friend's computer from scratch.
The DVD drive was on Primary IDE jumpered master, the hard drive on Primary IDE jumpered slave. It has a memory card reader that is assigned 4 drive letters for 4 types of memory cards.
Setup assigned H to the partition Windows was installed on, not C.
C, D, E,.F - memory card reader
G - DVD drive

I changed things - DVD drive to on Primary IDE jumpered slave, the hard drive to on Primary IDE jumpered master. I unplugged the USB connections to the front panel memory card reader.
I ran Setup from scratch again - the partition Windows is installed on was assigned C.
D - DVD drive.
I plugged in the USB to the memory card reader - E, F,G, H
(You can change any drive letter assignment, C to Z, except the one assigned to the partition Windows booted from, in Disk Management.)

When you go to Run , type.. cmd

The drive letter at the beginning of the resulting line is the same as the drive letter of your loaded Windows installation.

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June 26, 2011 at 22:19:55
Thank a billion for your concise instructions and insight.
I spent most of the day reviewing these steps and options.And testing them..
But to no avail. It appears to be in a vicious loop of Blue screen hell. Coming up with a different file as a reason for it each time now. It has basically stopped booting in safe mode. Making any options to further investigate impossible. So I am at the point of formatting and starting fresh. However I'm concerned that any potential virus/malware will prevent a fresh install( as I've had that happen with a previous desktop.) or that the Hard drive is damaged altogether..

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June 27, 2011 at 06:52:13
See the part in response 5 about testing your hard drive.

If it's failing, that's probably the cause of your problems, and you'd be wasting your time trying to get Windows to work by installing it again from scratch with that hard drive.

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June 27, 2011 at 09:27:01
In safe mode try sfc.exe /scanonce and reboot.

Even if your sp is off you can put that back.

1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.

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June 27, 2011 at 13:58:37
sfc will not run in Safe mode.

If you type cmd before you type sfc /scannow or
sfc /scanonce you'll see the error message.

." However I'm concerned that any potential virus/malware will prevent a fresh install( as I've had that happen with a previous desktop.)"

When you install the operating system from scratch (after having booted the computer from the CD or DVD), you either delete the partition Windows was installed on and make a new one, or you delete the data on the partition Windows was on, BEFORE you install the operating system. Either way, even if you do have malware on the hard drive, it can't run if it isn't there, and it can't run without there being a working operating system for it to run in.

There is an extremely remote possibility you might have a boot sector virus, which wouldn't be deleted until the operating system was installed and re-wrote the data in it, but that's extremely unlikely these days if you were consistently using any anti-virus software at all - it's been many years since I've heard of anyone getting that.

It sounds like it's likely your hard drive is failing.Test it with diagnostic FIRST, if you haven't already done so

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