Windows Error "Error loading operating system" - causes and remedies

The “Error loading operating system” error can be expected when you install Windows XP and restart. While the computer starts up, its BIOS and CMOS check the hardware and OS. If something is wrong, the BIOS and CMOS will not start the operating system. When such an error occurs, you will not be able to get to the Windows desktop. Other operating systems, such as Windows Vista or Windows 7, will not display this message. If your problem is that you cannot boot Windows Vista or Windows 7 without this message, just try restoring the boot from the Windows installation disk.

Error Correction "Error loading operating system".

What does this error mean?

Error message: “Error loading operating system” with a black screen (translated as “OS loading error”) is an annoying problem that users often experience when trying to boot their Windows PC. The startup problem usually occurs after a new installation of the Windows operating system, a sudden power failure, a crash or a reboot. What exactly makes your PC OS not boot properly? How can I solve the problem of "operating system boot error"? Whenever Windows (7 and newer) turns on and starts up, its BIOS and CMOS start working on the OS setup, check the hard drives and then load the OS. During the process, if there is any problem on the hard disk, the operating system does not start and you cannot open your desktop. This means that your OS has the following problems that prevent the OS from loading properly:

  • The system partition of the hard drive is damaged due to a sudden power outage, virus infection or recording.
  • OS files and folders are damaged.
  • BIOS does not support hard drive.
  • Several hard drives are connected to your PC, which is why the main hard drive containing the OS and system applications is now not detected.
  • HDD has become physically damaged.

Causes of the problem

The BIOS loads the 1st sector from the hard drive (Master Boot Record), checks the 55 AA signature and transfers control to the Master Boot Record. The master boot record scans the partition table for the presence of the active partition, then loads the 1st sector from the active partition, verifies the 55 AA signature, and transfers control to the boot sector. The boot sector loads 15 additional sectors from the beginning of the disk (Volume Boot Record) and transfers control to the first additional VBR sector in Windows XP and the rest. Volume Boot Record loads the BOOTMGR file from the root directory of the boot partition into memory and transfers control to it.

BOOTMGR loads the registry branch Boot \ BCD and displays the boot menu. This means that BOOTMGR can run a memory test and set the boot in safe mode to prompt the user. But usually it loads winload.exe when the PC boots up normally (cold start) or winresume.exe (when the PC goes out of sleep mode). Winload.exe opens the registry branch SYSTEM, gets a list of drivers, loads NTOSKRNL.exe, loads drivers (* .SYS files) and transfers control to NTOSKRNL.exe. Winresume.exe loads the memory dump from hiberfil.sys and transfers control to it. The BIOS loads the 1st sector from the hard drive (Master Boot Record), checks the 55 AA signature and transfers control to the Master Boot Record.

The master boot record (in Windows 8) scans the partition table for the presence of active partitions. There is one active partition, so Master Boot Record is trying to load the 1st sector from the active partition, but the sector is outside the device sector counter or does not contain a 55 AA signature. Thus, the MBR issues an error message “Error loading operating system” and stops the machine.

How to fix a problem with the “Error loading operating system” code

By eliminating the problem of “Error loading operating system”, there is a chance that you may lose important data from partitions on your PC. If you do not have a backup of your data, professional data recovery software is the only way to recover lost files and folders. One of the widely used programs is Stellar Data Recovery Professional for Windows. It is a safe and secure way to recover all types of files and folders, whether they are Word documents, PowerPoints, PDF, Excel, photos, audio or video. Software is the best solution for recovering lost data in Windows. This tool supports recovery from FAT, NTFS and exFAT partitions. There are many methods by which you can fix the problem “Error loading the operating system." It is recommended to choose the right one according to the required situation.

  1. You can perform Windows CHKDSK if there is a problem with the hard drive. This Windows tool scans and fixes a bad sector on a hard disk.
  2. Another way is to restore the master boot record (MBR) information of the computer in order to fix inappropriate hard drive sections and settings.
  3. When the BIOS on the motherboard does not support HDD or it is not configured properly in CMOS, a BIOS update is also a workable solution.

Consider these and other effective methods in more detail.

Scan and repair with the Windows CHKDSK tool

It is important to first try to determine the cause of your problem and then act accordingly to fix it. To eliminate the problem with the hard drive, first run Windows CHKDSK. This is a built-in Windows tool for assessing the overall state of the hard drive. Windows CHKDSK scans and repairs bad sectors and errors, if any. Steps for implementing Windows CHKDSK:

  • Right-click the disk to check for errors.
  • Select "Properties"
  • Click on "Tools"
  • In the "Error Checking" section, click "Check."
  • A dialog box appears with options for checking the disk, registering and scanning for bad sectors.
  • Click "Start".

Scanning will correct and show if there is physical damage to the hard drive.

Update system BIOS to latest version

Be especially careful when updating the BIOS version. This is due to the fact that during the process the BIOS firmware may be damaged due to a sudden power loss. Therefore, you will not be able to load and access your data. Thus, always follow the guidelines for backing up all important files before performing a BIOS update, so that you can access and work with them later. To update your PC's BIOS, follow these steps:

  • Find the brand and model of your motherboard. Check it out in your motherboard user manual.
  • Determine the current BIOS version - to do this, open the System Information application. In the search field, enter "System Information" and select "System Summary". The BIOS version will be displayed here.
  • Download the latest BIOS update - visit the website of the motherboard or laptop manufacturer. Find a model from the list of available downloads, go to the BIOS update.
  • After downloading, run the BIOS update.

Reboot the PC after updating the BIOS.

Recovering MBR hard disk information

Each Windows OS has its own way of recovering MBR information. Read the instructions for your version of Windows on the Internet and return the MBR information to resolve the “Operating System Boot Error” problem. Requirement: Windows installation CD / DVD.

  • Restart the PC and boot from the Windows installation CD.
  • In the message “Press any key to boot from CD or DVD” press any button.
  • Click “Recover Your Computer”.
  • Select “Troubleshooting”.
  • Select a command prompt.

When the command line loads, type the following four commands and press Enter after each. Wait until the end of each operation:

  • bootrec / FixMbr
  • bootrec / fixboot
  • bootrec / scanos
  • bootrec / RebuildBcd

Reboot the PC.

Reinstall Windows Operating System

When the program files and folders on your Windows OS are damaged, the message “Operating System Boot Error” appears on the PC. Thus, if the above methods do not solve the problem and the hard drive also works properly, the last option is to reinstall Windows. Reinstalling Windows returns you to a fast PC.

Other causes of the error and how to fix it

Such an error occurs when computer owners start the PC when the PC loads its OS incorrectly due to some problems with the hard drive, damaged OS files / folders, incorrect MBR information (master boot record) of the PC hard drive and much more. This computer OS boot error often occurs with a black screen in such circumstances:

  • After installing or reinstalling the OS.
  • Reboot your PC after a sudden power failure, power surge, or computer crash.
  • When the PC is seriously damaged or attacked by viruses, etc.
  • When HDD is not partitioned properly.

As we mentioned above, these errors when booting the computer cause OS problems when it loads incorrectly, as usual. Here are some more possible reasons why such errors occur on your computer:

  • Hard disk crashes. No matter what version of Windows OS you use on your computer, such errors when booting the computer can often be caused by hard crashes. Why? When people try to download the desired PC, the computer often needs to read the information about the OS stored on the PC and, finally, perform a smooth setup of the computer. However, when the hard disk is somehow damaged or partitions that contain a lot of important operating system data, are filled with bad sectors or are physically damaged, the PC often will not be able to recognize the necessary information of the OS and force it to boot unsuccessfully.
  • Information about the MBR of the hard disk of the computer is incorrect. Regular booting of the boot computer can also be negatively affected or stopped by incorrect MBR information of the hard disk, which can often cause the PC to find and read the necessary data from the actual partitions of the hard disk within a few seconds. As soon as the MBR information on the hard disk becomes incorrect, the probability of a PC OS boot error will also be increased.
  • OS is faulty. Except for some problems with HDD, which can adversely affect the overall load of your PC's OS, problems arising from the PC OS, such as some damaged boot files or OS configuration files of your computer, can also cause a problem.
  • Incorrectly installed HDD, if several hard drives are used on one PC. It is always necessary to specify the main HDD (which is used to store an important operating system, applications, etc.) from the list of other additional disks so that the PC can automatically recognize the disk with the operating system and load the operating system of the computer.
  • HDD is not properly partitioned. Incorrectly-labeled hard disk will also affect the boot of the PC operating system with daily use.

Additional recommendations

Regardless of what causes your PC to pop up due to an operating system boot error, there are several ways you can easily eliminate such errors:

  1. Check if your PC's HDD is well recognized.

Regardless of whether your PC's errors are caused by booting the operating system of the hard disk or not, check the status of the hard disk right now. Try to access the files inside and see if you have some kind of error on an unformatted disk or related unavailable disk errors that can stop further data usage. Then open "Disk Management" and check whether it is displayed there normally. The file system of your internal hard drive should not be converted to RAW. Then run the CHKDSK scan on this hard disk to see if there are too many bad sectors or other physical damage. If after all these checks you do not get anything unusual, your HDD should be in good condition. Then exclude this item and continue to check other paths.

  1. Recover MBR information on your hard drive.

If the MBR information on the hard disk of your PC is not displayed correctly, the most practical or workable way to fix this operating system error is to restore the MBR information back. Therefore, regardless of what you did before, immediately stop it and find the right steps to recover the MBR information of the disk. Nowadays, because in different versions of the operating system, people are differently allowed to recover MBR information on the hard disk, it is better to first check the current Windows version for your PC and go on to read the relevant articles / topics to continue. Then restart the PC and see if the operating system boot error occurred again.

  1. Reset PC to factory settings.

If you have not left important data on a PC hard disk or other storage devices inserted now, you can also restore your PC to its factory settings and see if you can continue to use it functionally, as before. But, if you really disassembled important computer data there, you should not immediately restore it to factory settings.

Learn to avoid other computer problems:

  • Before checking the disk, reinstalling the PC operating system, or restoring the factory settings, back up important data on your hard disk.

HDD is often used to store very important or valuable files, songs, videos, and similar information. Before performing any disk check, reinstalling the computer's operating system, or restoring the PC to its original settings, in case of unexpected deletion of unsaved data from the disk, first copy the useful data to other storage devices.

  • Try to recover your computer data using the file recovery software on your hard drive.

Regardless of whether you backed up computer data elsewhere, you can scan your desired HDD or external HDD and recover disk data using file recovery software after deleting or losing PC data due to improper OS loading, reinstallation, formatting / rewrite hard disk, etc. You can use the method described below to back up files from Windows XP, Windows Vista and Windows 7 and Windows 8.

First, you need to have a Windows installation DVD. If you don’t have one, you can download the official ISO image from Microsoft. You need to burn it to DVD or create a bootable USB-drive (at least 4 GB). To do this, you can use the Windows 7 USB / DVD Download Tool from Microsoft. After receiving a bootable DVD or USB, insert it into the PC and reboot it. The message “Press any key to boot from CD or DVD” appears. If you do not do this, you will need to choose a DVD or USB as the boot device. To do this, you will need to press a key on the screen with the logo of the manufacturer of your PC. It depends on the manufacturer: for HP, this is usually ESC or F9, for Dell you must press F12, etc.

After booting from a DVD or USB, you will see the message “Windows loads files, ” and then the Windows Starting Windows startup screen will appear. Select a keyboard layout and click Next. Then select “Recover Computer”. Let the system search for Windows installations. Then click "Next." If Windows installations were not found (or if you are using Windows XP), you will see the error message "Select a backup of the system image." Just click "Cancel" in both windows. In any case, you will be taken to the System Recovery Options screen. From here you can try to use System Restore or Startup Repair to see if you can fix your PC. To back up files, select “Command Prompt”.

Type Notepad and press Enter. Click File-Open. In the File Type field, select All Files. Now you can go to “Computer” (on the left) to see your sections. Find the files that you want to back up, right-click on them and select "Copy." Usually your files are located in C: \ Documents and Settings \ UserName in Windows XP and in C: \ Users \ UserName in Windows Vista or Windows 7. Insert the external HDD or USB-drive, go back to “Computer” and insert them there . Please note that you will not see any progress dialogue. Be careful not to double-click the file, otherwise it will open in Notepad. If Notepad hangs, you can return to the command prompt, type in “taskmgr” and use the Task Manager to shut down Notepad, and then start it again. When you're done, close all windows and reboot the PC. Please note: if you have a lot of files to back up, this Windows Preinstallation Environment (Windows PE) will restart every 24 hours.

Bug fix with third-party software

An operating system error often occurs when the BIOS incorrectly detects the HDD or does not support the capacity of the hard disk on which you are installing Windows. To resolve this issue, update the BIOS of the computer's motherboard. Then make sure the HDD is properly configured in the CMOS setting and can be detected. Then try changing the “Access Mode” on the hard disk on the LBA. The next step will be fixing problems with partitions. Incorrect hard disk and partition settings (including partition table error, MBR error, and incorrect active partition) will also result in an operating system boot error. To completely and effectively fix operating system boot errors, you can use Fix Genius. This software has a user-friendly interface and ensures that it is simple enough for every computer user, regardless of their skills.

  1. Create a bootable CD.

You need to use a boot disk containing a system from which you can boot. Burn the boot disk as follows:

  • Insert a blank CD, DVD or USB flash drive into another computer.
  • Download, install and run Fix Genius on this computer.
  • Click the “Write” button in the main interface of the program.

After some time, a bootable CD will be created.

  1. Boot the computer from the CD. Now let's turn to the computer with system errors.
    • Insert a bootable CD into it.
    • Press the Delete key, F8 or F2, to access the BIOS setup.
    • Go to “Boot Device Select” and press “Enter”.
    • Select the CD as the first boot device.
    • Press F10 to save the changes. Your computer will automatically restart and gain access to the system recorded on this CD.
  2. Correction of errors when loading the operating system. After logging in, you will enter the Fix Genius interface in Win PE. Select Windows Recovery / Solution Center / Failed to Download. There are several fixing tools. Try "Repair MBR", which may be the main cause of the problem "Error loading the operating system."
  3. Smash the hard drive. If the error still occurs, you may need to use Partition Manager on the Disk Tools tab to split the HDD before installing the new Windows system.

So now you do not need to worry anymore if you encounter a computer boot error while loading the operating system while trying to boot the computer. Try the above methods to troubleshoot computer errors caused by any of the hard disk problems or damaged operating system files. If in the process of fixing the operating system boot error you lose system data, Stellar Data Recovery Professional for Windows is a reliable solution for recovering lost files and folders.