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Get the fix for the error <strong>Error loading operating system</strong> on <strong>Windows XP,</strong> <strong>Windows Vista </strong>and<strong> Windows 7</strong>.
<h2>About "<strong>Error loading operating system</strong>"</h2>
[kbintro]
<h3><span id="Description_and_Symptoms">Description and Symptoms</span></h3>
The error messages, alerts, warnings, and symptoms below are tied to this error.
<h3>Symptom 1: "<strong>Error loading operating system</strong>" error screen on startup</h3>
This error shows when your computer's BIOS doesn't support the capacity of the hard disk where you are installing Windows XP or it's not properly installed.

Issues with your hard disk drive's partition can also be a major cause.

<strong>Alternative error messages.</strong> There are no other known alternative messages for this boot error, except the "Error loading operating system" text that appears on your computer's black screen at startup.

[caption id="attachment_446" align="alignnone" width="980"]<a href="https://neosmart.net/wiki/wp-content/uploads/sites/5/2013/08/error-loading-operating-system-error.png"><img class="wp-image-446 size-full" src="https://neosmart.net/wiki/wp-content/uploads/sites/5/2013/08/error-loading-operating-system-error.png" alt="Windows Error: Error loading operating system" width="980" height="536" /></a> The "Error loading operating system" error[/caption]
<h2>Causes of this Error</h2>
This error has been known to occur as a result of one of the following causes:
<h3>Cause 1: The hard drive capacity is too big</h3>
The most common cause of this error is a hard drive that is too large to be supported by an outdated BIOS.
<h3>Cause 2: The hard drive partition is damaged</h3>
<span style="line-height: 1.5">The hard drive's partition may become damaged because of disk write errors, power outages or virus attacks. If that's the case, the operating system cannot access the system files to boot properly and the loading process is halted.</span>
<h2>Fix: Use Easy Recovery Essentials
<span id="Fixing_8220Fatal_INT18_Boot_failure8221_on_Windows"></span></h2>
[easyre error="Error loading operating system" bootscreen="xp-vista-7-8-10"]
<h2>Fix Error loading operating system in Windows XP</h2>
You can fix this error without a Windows XP installation disc as you don't need to boot into its Recovery Console.
<h3>Fix #1: Check your hard drive status in BIOS menu</h3>
Your computer may not see the hard drive correctly and can't boot into XP. You can check its status in BIOS (or CMOS Setup), but the step to access it depends on your computer's manufacturer.
<p class="info">Press one of these keys to enter BIOS/CMOS: <kbd>DEL</kbd> or <kbd>F1</kbd> or <kbd>F2</kbd> or <kbd>ESC</kbd>.</p>

<h3>Fix #2: Recreate the partitions</h3>
If your hard disk is setup correctly, you can recreate the partitions by installing Windows XP again.

The "Error loading operating system" error is more likely to appear if your partitions were also changed by another system before installing XP, e.g. a Linux distribution.

When you reinstall Windows XP, make sure you delete all partitions and create the partitions you need to install XP.
<h3>Fix #3: Update the BIOS</h3>
If none of the above fixes works for you, you can try and update your computer's BIOS. When starting up your computer check the messages at boot to determine your motherboard's manufacturer.
<p class="info">Press <kbd>Pause</kbd> key at boot to pause the loading messages.</p>
You can also check the BIOS version when accessing BIOS Menu/CMOS Setup. Go to Fix #1 above for the available keys to access it.
<h2>Fix Error loading operating system in Windows Vista</h2>
[setupcd]
<p class="info">You can also try the solutions from Windows 7.</p>

<h3>Fix #1: Run System Restore from the disc</h3>
This solution works if you have System Restore enabled on your Windows Vista.

The steps for restoring your PC with System Restore:
<ol>
 	<li>Insert the Windows Vista install disc</li>
 	<li>Restart your computer and boot from the install disc</li>
 	<li>Press a key when "Press any key to boot from CD or DVD" message appears on your screen</li>
 	<li>Click on <strong>Repair your computer</strong> after selecting a language, time and keyboard method</li>
 	<li>Select the drive where you installed Windows (usually <code>C:\</code>)</li>
 	<li>Click<strong>Next</strong></li>
 	<li>Select <strong>System Restore</strong> from the <em>System Recovery Options</em> window</li>
 	<li>Follow the System Restore instructions to select a restore point</li>
 	<li>Restore your PC by clicking Finish</li>
</ol>
<h3>Fix #2: Use Startup Repair</h3>
<ol>
 	<li>Insert your Windows Vista install disc</li>
 	<li>Restart your computer and boot from the CD</li>
 	<li>Press any key when you see "Press any key to boot from CD or DVD"</li>
 	<li>Click <strong>Repair your computer</strong> after selecting your language, time and keyboard method</li>
 	<li>Select the drive of your Windows installation and click Next. The standard drive is usually <code>C:\</code>.</li>
 	<li>Select <strong>Startup Repair</strong> and wait for the process to finish.</li>
</ol>
<h2>Fix Error loading operating system in Windows 7, Windows 8 and Windows 10</h2>
[setupcd]
<h3>Fix #1: Use bootrec.exe and rebuild the BCD</h3>
<code>bootrec.exe</code> is a tool built in the Windows Recovery Environment (Windows RE) that you can use to troubleshoot and repair the error. The steps for accessing bootrec.exe to rebuild the master boot sector:
<ol>
 	<li>Insert your Windows 7 install disc</li>
 	<li>Restart your computer and boot from the CD</li>
 	<li>Press any key at the "Press any key to boot from CD or DVD" message</li>
 	<li>Choose <strong>Repair your computer</strong> after you select the language, time and keyboard method</li>
 	<li>Select your Windows installation drive (usually <code>C:\</code>)</li>
 	<li>Click <strong>Next</strong></li>
 	<li>Select <strong>Command Prompt</strong> from <em>System Recovery Options</em></li>
 	<li>Type the following command and press <kbd>Enter</kbd>:
<pre>bootrec /FixMbr</pre>
<pre>bootrec /FixBoot</pre>
<pre>bootrec /ScanOs</pre>
<pre>bootrec /rebuildBcd</pre>
</li>
</ol>
[caption id="attachment_4708" align="alignnone" width="980"]<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/bootrec1.png"><img class="wp-image-4708 size-large" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/bootrec1-1024x768.png" alt="bootrec utility results screen" width="980" height="735" /></a> bootrec utility results screen[/caption]
<h2>More Information</h2>
<h3>Linked Entries</h3>
<ul>
 	<li><a href="https://neosmart.net/wiki/bootrec/">bootrec</a></li>
</ul>
[partial name="partial_moreinfo" versions="xp,vista,7"]