NTLDR not found on Windows XP

April 24, 2011 at 09:48:47
Specs: Windows XP SP2, 2 Gb
I was working on my PC without issue and suddenly the Blue Screen of death flashed up and my PC rebooted. My PC has been working for the last 18 months without issue.

Upon reboot it displayed message NTLDR not found Press (the almighty) F1 key to restart.... that just lead to a cycle of failed reboots. I'm able to boot into recovery console from my Windows XP CD.

When I bring up console it list two drives #1 is F: and #2 is D:. The Strange thing is that my normal C:\ Drive is showing up as the D:\ drive. The F: drive was an old windows XP IDE drive used for storage; it’s not set as Master or bootable. So not sure why they are listed in this order; unless it has to do with F: being IDE, and D: being SATA controller. C: was set as the SATA Primary boot drive.

I looked at the directory of D: and sure enough I can see Programs that I had added just a week ago. I ran chkdsk /p and no errors on any of the 5 physical drives installed in my computer.

MS and other recommend copying over new NTLDR and ntdetect.com files from CD to boot drive. I did copy them over to the D:\ (where they already existed); first renaming the original files with the "old" file convention. I re-attempted re-boot but was un-successful.

I then ran a "bootconfig /scan" and it failed. Said it could be related to corrupt file system (dah). I said to run chkdsk which I had done previously on all of the drives and resulting in no errors found.

I'm thinking my next step is to run Fixboot and Fixmbr.. But before I do this, I thought it would be a smart idea to make this post and see what others suggest... or have done to correct the problem. I don't think there is an "Undo" for either of these commands. As well I'm questioning if I should run these commands against the D: drive which has a Windows directory and all the normal files you would expect to see. Or run against the C: drive which appears to only have data files on it.

Additionally I ran the parting tool to check if all the expected drives and portions were present. All drives and portioned are present; NTFS configured.

See More: NTLDR not found on Windows XP

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April 24, 2011 at 10:59:30
1st - backup your drive - complete - better safe than sorry. There is no undo for many "fixes".
2nd - you are on the correct track. The recovery console has worked for me in the past, but not always. Give it 80% chance to correct your problem. Run fixboot. If that doesn't fix it, run fixmbr. One does file maintenance, the other addresses the master boot record. I'm leaning toward MBR being the problem. Especially with that other drive being installed.
3rd - the drive letters change depending on boot order and partitioning. The OS can assign drive letters differently than the BIOS, which throws a curve into the mix.

Best wishes!

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April 24, 2011 at 11:20:58
The OS can assign drive letters differently than the BIOS

Of course it will as the OS always assigns drive letters, each and every time it boots. The BIOS has nothing at all to do with drive letters, knows nothing about them and cares even less. The BIOS deals only in numbers.

If you think about it it makes sense. A PC can run many different type of Operating Systems. Not all of them use drive letters, So why would the BIOS allocates drive letters that are never going to be used.

The drive letters can change unexpectedly, especially after installing, removing or formating a hard disk but that is entirely down to the Operating System. Nothing at al to do with the BIOS. .



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April 24, 2011 at 13:53:15
i do agree with Stuart, the BIOS does not have to do anything with the drive letter at all. The drive letter is assigned when partition manager and volume manager is initialized.. NTLDR comes far ago. NTLDR does not read drive letters nor it can.NTLDR undestand the numbers format used by boot.ini.

@modify.hardware ..Just FYI on "One does file maintenance, the other addresses the master boot record. I'm leaning toward MBR being the problem" regarding Fixboot and Fixmbr.

Lets see how windows initial boot steps goes.

1.ROM BIOS checks for 1st bootable disk (assume HDD0)
2. BIOS transfers the control to first sector of HDD0 called as MBR.
3. MBR Consists of 512 Bytes, First 446 bytes contains the MBR bootable code and rest of 64 bytes contains the Partition table.
4. Each partition entry is of 16 bytes starts with wither 00 or 80 (Hex) 00 or 80 is boot indicated feild,subsiquent bytes indicates starting Cylinder Head and Sector etc,.
5. If the starting hex value of a parttion is 80 , it means its Active or System partition.
6. the MBR code (446 byte) will now jump to the partition with the starting value 80. The MBR code CANNOT read the filesystem inside the partition.
7. the MBR code will locate the first sector of active partition (the partition with 80 value) which is known as boot sector.
8. the boot sector has information about the filesystem type and a read only filesystem code which could just read the root of the partition (not subfolder or folders).
9. Windows XP bootsector is desgined to locate ntldr from the root of the partition.If its windows vista or above (windows 6.0 or above) it will look for bootmgr.
10. Now, The if the Boot sector does not finds NTLDR in the root it will say "NTLDR is missing " , if the filesystem is FAT32, it will say "Boot:NTLDRP not found"
11. above error can also come if the bootsector is itself corrupt. NTLDR is missing text string is hard coded in "boot sector" so i think there is no way MBR corruption can cause NTLDR missing. If MBR is corrupt, it will simply not go till BootSector.

the FIXMBR command just re-writes the first 446 bytes of MBR.so it will not harm anything (but its better to be safe as you said)
the Fixboot command re-writes the Bootsector of the partition.

Hope it make sense and help you answer questions more easily.

I Do apology for making a long explanation :)

Subhash Chandra.

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April 24, 2011 at 15:42:51
The drive letter is assigned when partition manager and volume manager is initialized.

That is not correct either. The drive letter is assigned each and every time the computer boots. Until such time as the OS kernel is loaded, drive letters do not exist. Until then the OS is using the numbers seen in boot.ini. No mention of drive letters there, There is a set sequence to the assigning of drive letter and if nothing changes, each drive gets the same letter at each boot.

The only variation to that is if a drive letter is hard coded to a particular drive has happens with the system and boot drive and that information is stored in the registry. Something that only exists and is usable after the Operating System is installed and able to create and modify the registry.. A drive letter will only be allocated once a partition is formatted and to do that you need some kind of Operating system running, even if it is only the cut down version that is in use during the installation process..

When booting from the Windows XP instalaltion CD it will often allocate different drive letters to existing partitions becasue at that stage the installation programme does not have access to the registry. Sonneting that has caught a few people out and they have ended up deleting the wrong partition becasue the drive letter has changed.


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April 24, 2011 at 18:14:46
I agree What you said above is correct . I have one doubt though..

The drive letter is assigned when partition manager and volume manager is initialized.

That is not correct either. The drive letter is assigned each and every time the computer boots. Until such time as the OS kernel is loaded,

not sure how you think its not correct..you yourself said that drive letter is assigned each time the computer boots. isnt; that what i said ?
What i said was 2 of the steps of windows boot sequence.Partition manager and Volume manager initialization.After that the Mount manager assigns drive letters to the partition/volumes.defiantly it happens when the kernel is finished initialization.

you did mentioned about registry..
The Mounted DosDevices key contains the Drive letter and 12 bytes value.

1. First 4 bytes are used for Disk signature in reverse order.
2. The next 4 bytes are double of Partition/Volume starting sector number.
3. And the rest 8 bytes of Volume starting sector . Filled with extra zeros to complete 12 byte.like

this key is read by mount manager each time windows boots up and assign appropriate letter. As the key is part of os system hive , the letter is releted to that OS only. If system is booted through a PE, it may use different letter. most often first drive as C:. But it can behave other way as well.some time i have seen our custmuers loosing data just because PE assign different letter then original and due to that confusion they selected wrong drive.. by chance if someone comes up to this post be aware :)

Subhash Chandra.

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April 25, 2011 at 02:42:19
I misunderstood what you meant by partition manager and volume manager initialised. I was thought you meant when the partition is formatted. Otherwise we are in agreement.


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April 25, 2011 at 11:45:02
Not sure how I can backup anything at this point. The system will not allow me to copy anything to Drive A: keeps coming back as Access Denied. I can access the A: drive and read a floppy (wow did I actually write floppy. Yikes). The good news is that I do perform regular nightly data file backups to my HP Media Server. So worse case I will need reload the system, all applications, and the 16 hrs of work that didn't make it into the last backup. And of course I'm not able to access the directories where the last 16hrs of work was completed. And the Copy command does not support wildcards.. any last minute ideas ?

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April 25, 2011 at 12:10:24
all many thanks for all of the detailed discussion and I really appreocate the education.

So get the point that the Drive letters are basically useless in my current state. Which was confirmed when I left and came back into the repair console, the drive letters changed from the first time I used the console...

I'm about to run the fixboot... but my questions are as follow:
1) Since drive letters are meaningless at this point I'm not sure what drive I should be in when I execute fixboot? How can I tell which drive to execute the Fixboot command? and when I entered into the command it asked "Do I wnat to write a new bootsector to the partition F:" (plug in your favorite drive letter here.) I responded with an N this time since I was unsure which drive & partition to execute the command. Is there harm in doing this in all drives and partitions.. I'm asumming worse case the answer is YES. I looked around in MS and found they had little to nothing to help me on line.

2) Within the Repair console how do I change to a directory like "Documents and Settings" I tried variation of CD CHDIR with and without " " , etc.. "access Denied" error.. humm.. If I could get to the directory where my last 16hrs of work was saved and able to copy to another internal drive I won't feel so miserable if I need to reload everything..

3) Risk in executing Fixmbr. Will it fixes my boot up problem so I can get back into windows, but the price I pay is all my applciations and files are not longer accessible. Is that an expected result or unexpected result?

So maybe I'm being over cautuious.. I just hate to screw myself into the ground because I didn't perform due dilligence with the team here.

Again many thanks for helping me out here.. can you tell I'm a little nervous and out of my element with running these commands .. ; -(

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April 25, 2011 at 12:23:21
... might be worth a tinker in the bios ide, sata settings(?)

... I'm not sure what you're using to bootup to console whether it "throws-in" sata driver(s) so it then see's your drives(?)

... some info in this thread... #5

... how old is the cmos battery? .... my two cents worth!
Angel Decoy
... there is logic to this madness!
Grrrrrrrrrrrrrrrrrrrrrrrrrrr... .im

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April 25, 2011 at 12:57:03
rm722 bootup with the created "iso" : http://www.hirensbootcd.org/download/

... select mini xp @ bootup a "plethora" of tools including backup's with gui interface.
Angel Decoy
... there is logic to this madness!
Grrrrrrrrrrrrrrrrrrrrrrrrrrr... .im

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