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Get the fix to the <strong>NTDETECT failed</strong> boot error message and other NTDETECT&#46;COM problems affecting <strong>Windows XP, Windows 2000 </strong>and<strong> Windows Server 2003</strong><strong>.</strong>
<h2>About "NTDETECT failed"</h2>
[kbintro]
<h3>Description and Symptoms</h3>
The error messages, alerts, warnings, and symptoms below are tied to this error.
<h4>Symptom 1: NTDETECT failed <span id="Symptom_1_Fatal_INT18_Boot_failure_error_screen_on_startup">error screen on startup</span></h4>
NTDETECT&#46;COM is a helper program invoked by NTLDR (the Windows XP and Server 2003 bootloader) to detect basic hardware required to start the operating system. NTDETECT passes this hardware information back to NTLDR which then gives control to ntoskrnl.exe, the Windows NT kernel. However, if NTDETECT.com is not found, or is unable to execute properly, then a message stating "ntdetect failed" may be displayed. This message is also often encountered when attempting to boot into the Windows XP setup CD.

For more information on <a href="http://neosmart.net/wiki/mbr-boot-process/">how computers start up</a> and <a href="http://neosmart.net/wiki/windows-xp-boot-process/">how the Windows XP boot process works</a>, please refer to the respective pages in our extensive wiki and knowledgebase.

<a href="/wiki/wp-content/uploads/sites/5/2013/08/ntdetect-failed.png"><img class="alignnone" src="/wiki/wp-content/uploads/sites/5/2013/08/ntdetect-failed.png" alt="NTDETECT failed error screen" width="980" height="250" /></a>
<pre>Setup is inspecting your computer's hardware configuration...

NTDETECT failed</pre>
<h3>Causes of this Error</h3>
This error has been known to occur as a result of one of the following causes:
<h4>Cause 1: Incompatible NTDETECT version</h4>
NTDETECT&#46;COM ships with Windows and is typically installed from the Windows setup CD.

Older versions of NTDETECT have problems reading NTFS filesystems from newer drives and identifying/communicating with newer hardware. If NTDETECT&#46;COM is downgraded to an older version for some reason (incomplete or interrupted Windows installation or setup attempt, incorrect Windows Update hotfix installed, etc.), this error may present.
<h4>Cause 2: NTDETECT file is missing or is corrupt</h4>
NTDETECT, located in the root of the boot partition on disk 0, is an essential part of the boot process. If it is accidentally deleted, moved to another folder, or becomes corrupt, probably because of user errors, sudden loss of power during writes to the boot partition, or virus infection, then this error appears and the boot process is halted.
<h4>Cause 3: Compressed NTDETECT&#46;COM file</h4>
NeoSmart's computer troubleshooting engineers have identified that one of the most common (yet unidentified) cases of "NTDETECT failed" errors is as the result of incorrect or improper compression of the boot partition.

Key Windows boot files must never be compressed, and many 3rd party products will attempt to compress <em>all</em> files on the system partition — including NTLDR, BOOT.INI, and NTDETECT&#46;COM — resulting in this error. Also attempts at compressing the boot partition with DoubleSpace, DriveSpace, or manually enabling NTFS file compression will cause this error to occur as well.
<h4>Cause 4: Fragmentation of NTDETECT&#46;COM</h4>
On NTFS or FAT partitions with a small enough cluster size, NTDETECT&#46;COM may be written to non-adjacent clusters through an occurrence known as file fragmentation.

It is unknown whether any of the NTLDR versions that Microsoft has shipped over the years are capable of reading an NTDETECT&#46;COM file spread over multiple non-consecutive clusters on-disk, and NTDETECT should be defragmented to be stored on consecutive blocks on the filesystem to resolve this scenario.
<h2>Guaranteed Fix: Use Easy Recovery Essentials</h2>
[easyre error="NTDETECT failed" bootscreen="xp" guaranteed="true"]
<h2>Other fixes for NTDETECT failed in Windows XP</h2>
[setupcd]
<h3>Fix #1: Restore NTDETECT&#46;COM</h3>
If the NTDETECT file itself has become corrupted or damaged as a result of one or more of the scenarios explained above, or if an older/incompatible version of NTDETECT has been installed to the system partition, the following instructions will revert it to the correct, compatible version.

It is imperative that the correct Windows setup CD (i.e. with the correct service pack and correct 32- or 64-bit architecture) is used for the procedure!

If ntdetect&#46;com is in fact missing or corrupt, the user can restore the original ntdetect&#46;com file back from the Windows XP installation disc.

Here are the steps to do it:
<ol>
 	<li>Insert Windows XP install CD in the PC</li>
 	<li>Restart the computer and boot from the CD</li>
 	<li>Press any key to boot from the CD</li>
 	<li>Press <kbd>R</kbd> when the Windows Options menu is reached to access Repair Console</li>
 	<li>After this step, log into Windows by pressing <kbd>1</kbd> using the Administrator password</li>
 	<li>Use the following commands to copy the NTLDR and NTDETECT&#46;COM files from the Windows installation disk to the hard disk:
<pre>copy D:\i386\ntdetect&#46;com C:\</pre>
Where <code>D:\</code> is the install CD’s drive letter and <code>C:\</code> is a PC's Windows XP partition’s drive letter</li>
 	<li>Once these files are copied, remove the Windows installation disc from the disc drive</li>
 	<li>Restart the PC</li>
</ol>
Here is an example of what the PC's console output should look like once the NTDETECT.com file is restored:

[caption id="attachment_4062" align="alignnone" width="720"]<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/Restoring-ntdetect.png"><img class="size-full wp-image-4062" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/Restoring-ntdetect.png" alt="Replacing the ntdetect&#46;com file" width="720" height="396" /></a> Replacing the ntdetect&#46;com file[/caption]
<h3>Fix #2: Defragment NTDETECT</h3>
If the NTDETECT failed error message is caused by file fragmentation, it can be resolved by attempting to defragment either the individual NTDETECT&#46;COM file or the filesystem it is on. It is possible to defragment NTDETECT&#46;COM by using the free <code>contig</code> utility from Microsoft (originally developed by Sysinternals). Here are the steps to do it:
<ol>
 	<li>Download contig.zip from Microsoft <a title="contig" href="http://technet.microsoft.com/en-us/sysinternals/bb897428.aspx">at this link</a></li>
 	<li>Extract contig.exe from contig.zip</li>
 	<li>Launch a command process window (Start | Run | cmd.exe) and use CD to navigate to the directory you extracted contig.exe</li>
 	<li>Finally, run contig.exe against the NTDETECT&#46;COM file that should be defragmented:
<pre>cd Downloads
contig.exe D:\ntdetect&#46;com</pre>
</li>
 	<li>Wait for it to finish.</li>
</ol>
Here is an example of what the PC's console output should look like once contig.exe is done defragmenting the NTDETECT.com file:

[caption id="attachment_2414" align="alignnone" width="677"]<a href="https://neosmart.net/wiki/wp-content/uploads/sites/5/2013/08/contig-result.png"><img class="wp-image-2414 size-full" src="https://neosmart.net/wiki/wp-content/uploads/sites/5/2013/08/contig-result.png" alt="Defragmenting the NTDETECT&#46;COM file" width="677" height="392" /></a> Defragmenting the NTDETECT&#46;COM file[/caption]
<h3>Fix #3: Using chkdsk to repair filesystem errors</h3>
[partial name="partial_chkdsk_xp"]

Here is an example of what the PC's console output should look like once the chkdsk.exe is complete:

[caption id="attachment_4068" align="alignnone" width="720"]<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/WinXP_chkdsk.png"><img class="wp-image-4068 size-full" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/WinXP_chkdsk.png" alt="Windows XP chkdsk result screen" width="720" height="396" /></a> Windows XP chkdsk result screen[/caption]
<h2>More Information</h2>
<h3>Linked Entries</h3>
The errors below have been verified as being associated with or related to this problem:
<ul>
 	<li><a href="https://neosmart.net/wiki/mbr-boot-process/">MBR boot process</a></li>
 	<li><a href="https://neosmart.net/wiki/windows-xp-boot-process/">Windows XP boot process</a></li>
 	<li><a href="https://neosmart.net/wiki/ntldr-is-missing/">NTLDR is missing</a></li>
 	<li><a href="http://neosmart.net/wiki/ntdetect-not-found-missing/">NTDETECT missing or not found</a></li>
 	<li><a href="http://neosmart.net/wiki/ntldr-is-compressed/">NTLDR is compressed</a></li>
</ul>
[partial name="partial_moreinfo" versions="xp,server2003"]