Windows won't boot? Try these tips

When faced with the blue screen of death, you have options

Prepare for the worst

I've experienced my ugly share of Windows boot problems over the years: I've seen my laptop working perfectly fine at home, only for it to inexplicably quit on me when I try to start it up on an airplane a mere two hours later. That's why, wherever I travel, I'm prepared for a total crash of my machine -- and you should be too.

Create a Windows image

Keep an up-to-date image of your entire machine on a portable USB disk drive, and take it everywhere you go. There are some great third-party tools out there, but I tend to use Windows' built-in solution, which is available only on Vista or Windows 7. It gets the job done and is built into the startup repair tools (more on which in a moment). You'll find it right under Control Panel -> System and Security -> Backup and Restore -> Create a system image. XP users don't have this option, but there are a number of applications that will do the trick.

To speed up you restore times, try offloading all your larger and personal files (music, photos, documents, virtual machines, etc.) to a separate partition, but still let Windows back up both partitions. By doing so, you'll keep the system image size much lower and reduce image restore times for your system partition immensely. In case of an emergency, you can the system image (Windows, your applications, your user account data) and get back to work faster. Your D: drive should still be there -- and even if that's messed up, you've still got an image you can mount. To do so, use the Diskmgmt.msc command to launch Disk Management, go to Action -> Attach VHD, and select the secondary partition from within the image folder \Windows Image Backup\PC_NAME\Backup Date -- it'll be the one with the higher string number in the file name.

Restoring a partition

Keep the Windows DVD or a recovery CD with you

If Windows detects boot problems, it usually automatically runs the Windows Recovery Environment (or WinRE -- we'll discuss this in more detail below) and presents you with options to restore an image or perform various repair commands. However, if your hard disk is really screwed up for whatever reason, it might even affect the hidden recovery partition that contains WinRE. If you're using Windows 7 or Vista, in such situations you can use the Windows DVD, or the recovery CD that Windows backup creates right after it's finished creating your image. You can burn such a recovery disc any time by going to Control Panel -> System and Security -> Backup and Restore -> Create a system repair disc. You can also put WinRE on a bootable thumb drive.

WinRE offers tools to restore a botched disk

Restoring an image works in most cases, but it takes its time (even with the strategy mentioned above) and effectively destroys all data or settings created after you've set it up. It's a last resort.

Try some quick troubleshooting

Before really digging in and mucking with boot and system files, you should try these troubleshooting tips.

  • You can invoke a "Last Known Good" mode you by hitting F8 repeatedly just before the Windows boot screen appears -- it works more often than you might think, as it restores all changes made to your hardware profile and registry made during your last session (or successful boot). That's why it's smart to use this mode before you run Safe Mode. If that's not working, Windows Startup Repair and Safe Mode are your anchors.

  • I'd also advise you to unplug all devices from your machine: If you're staring at a black screen before or after the Windows logo appears and don't get any error messages at all, you're usually looking at some form of hardware detection error. In that case, unplug all USB devices, starting with hubs, that don't work. Next, try disabling all built-in devices, such as onboard Wi-Fi chips, sound cards, or LAN adapters. These things sometimes work wonders.

Safe mode is your new best friend

If your PC boots into Safe Mode, it's a great way to get things moving again. Obviously, your first priority should be to roll back drivers or uninstall programs that might have rendered your system useless – you probably know all that, so let's jump into some lesser known steps if all that fails.

Verify drivers

Windows features a well-hidden tool to help you detect driver issues. Run Verifier.exe and go to Create standard settings -> Automatically select all drivers installed on this computer. If Windows detects any driver issues, you'll be presented with a blue screen (on purpose!) upon next boot that'll tell you which drivers aren't running properly. Make sure that "Automatically restart" is disabled for system files: You'll find this checkbox under System Properties -> Advanced -> Startup and Recovery -> Settings. The blue screen will give you a file name and an error code that'll help you determine the problems source. To get back from this blue screen, invoke the "Last Known Good" configuration we discussed earlier to disable all driver checks. This is a good place to start to figure out which driver is acting up. Solution: Disable it, roll it back, or update it to the latest version (if possible).


Run msconfig and disable all processes that might interfere with Windows booting. First, go to the Services tab and check Hide all Microsoft services. Disable third-party services and see if your PC boots. If that worked, re-enable each service one by one to find the cause of your boot problem. Repeat this step with all Startup processes as well, if necessary.

Disabling third-party services that might interfere with your bootup process

Event viewer

Whatever is going on, it's highly likely that Event Viewer will catch it. Launch Event Viewer from your Start menu search, go to Custom Views, and take a look at all the critical Administrative Events.


Go to the details tab and find out everything about the service or process that's preventing Windows from starting up properly. In case the event isn't found here, go to Application and Services Logs and open up Microsoft -> Windows. From here, entries beginning with "Kernel…" are a good start for figuring out critical errors at boot time.

System File Checker

An inability to boot Windows might be caused by defective or replaced system files. To repair essential Windows data, open up a command prompt and type in

sfc /scannow
. This replaces all non-default OS files with the original ones and should get you back to normal in no time.


If Windows fails to boot because of a defective file (which will usually produce an error such as "Failed to load library xyz.dll"), try excluding this specific file from bootup. To do so, use Sysinternals Autoruns, try to find the file that's giving you trouble, and uncheck it.

Restore Windows logon

A third-party tool or a virus might have replaced your standard Windows shell (explorer.exe) with a different shell. Try to run Safe Mode and open up regedit.exe; if you don't see your desktop, use Ctrl-Alt-Del and open Task Manager to run regedit. Go to HKEY_LOCAL_MACHINE -> SOFTWARE -> Microsoft -> Windows NT -> CurrentVersion -> Winlogon, double-click Shell, and replace whatever is there with "explorer.exe".

Startup Repair

As we discussed earlier, Windows Vista and Windows 7 include the Windows Recovery Environment, or WinRE. If Windows fails to boot, WinRE should automatically launch its Startup Repair feature, which will try to repair corrupt disk data (using a superficial

check), restore the partition table, and fix boot configuration data (BCD). If it can't help, Startup repair asks you to restore the last system restore point.

As Startup Repair combines several troubleshooting techniques into one, it's likely to solve most boot problems. Check out Microsofts Technet to get a detailed overview on what gets fixed once you run Startup Repair.

Startup Repair goes to work

Use WinRE for full-on troubleshooting

Startup Repair didn't work? Then the root of your problem lies much deeper. It's likely that some essential master boot information, registry information, or file system data got very screwed up. For that, you need to use the full power of Windows Recovery Environment. Simply boot from your DVD, CD, or thumb drive (as described in above) to enter WinRE. From here, you should first try an older restore point. If that fails, walk through these steps to get your system up and running again.

Run chkdsk with its most thorough options

As mentioned above, Startup Repair runs a very basic version of

, which tries to find filesystem metadata corruption. While that's a good place to start, it's not anywhere as effective as running the utility with its more thorough options. For that, go to the command prompt and enter
chkdsk X: /f /r /b
(replacing the
with the driver letter from your system drive -- note that WinRE might have assigned D: or E:, and not C:, to your system drive). By performing this thorough
, you'll fix all errors on your hard disk, such as file system metadata and security descriptors.
will also check the entire volume for bad clusters, recover what's there to recover, and mark the clusters as bad in order to avoid new information being written to them.

Run memory diagnostics

Windows Memory Diagnostics, also part of WinRE, finds defective memory modules. Launch it and set it to "Restart now and check for problems." If it finds anything and you've got more than one RAM chip, try to remove one of the modules to see which one's not working.

Use the offline System File Checker

As mentioned above, the System File Checker will scan and repair the most critical system files. However, if Windows itself is too damaged, you might not get to Safe Mode at all. In such a situation, you can use an offline version of System File Checker to inspect your damaged Windows installation from inside WinRE. Type

SFC /scannow /offbootdir=d:\ /offwindir=d:\
(substituting the correct drive for your Windows partition for
if needed).

Restore the MBR and fix your system partition's start sector

Your master boot record may be damaged in case of a sudden power failure, or if you try to run Windows XP on a newer machine. To restore the MBR, boot into WinRE using your Windows DVD, the recovery CD, or a flash drive (see above) and go into the command prompt. Use the following commands to rebuild your MBR:

bootrec /fixmbr
bootrec /fixboot

Now that your MBR has been wiped clean, you'll need to rebuild the Boot Configuration Data, as outlined below, to set the boot information back up.

Rebuild the Boot Configuration Data

Windows' new boot loader, dubbed BCD (Boot Configuration Data), includes all boot information and parameters. If BCD is defective in any way, Windows simply fails to boot. If startup repair can't fix your problem, it's time to rebuild the entire Boot Configuration Data from scratch. From the command prompt, type in the following commands to rebuild the BCD:

bcdedit /export C:\oldBCD 
cd c:\boot 
attrib bcd -s -h -r 
ren c:\boot\bcd bcd.old 
bootrec /RebuildBcd

These commands will back up your BCD store, rename it (as a double-backup) and then rebuild the entire thing in seconds. The last command detects all currently running Windows versions and restores their boot data.

Reset system partitions back to Windows 7

If you get an "Operating system missing" error, and all the steps listed so for haven't helped, partition information might have been screwed up -- by an older backup-program, for example. In this case, you need to reset your system partition to the Windows 7 standard. Go to WinRE's command prompt and type in

bootsect /nt60 C:\
. This will mark your C drive as a proper active Windows 7 partition.

Wipe out boot infections once and for all

If your PC has been infected with a boot virus, you might be able to get rid of it using the steps detailed in the previous section. However, there's nothing hindering the virus from re-infecting the files once your system is up and running again. My advice: Go with one of the countless antivirus live CDs. Also give Windows System Sweeper (which isn't on the list in the first link) a try. It's a version of Microsoft Security Essential 2 that can be burned to CD/DVD or copied over to a bootable thumb drive.

Wipe out boot infections once and for all

If your PC has been infected with a boot virus, you might be able to get rid of it using the steps detailed in the previous section. However, there's nothing hindering the virus from re-infecting the files once your system is up and running again. My advice: Go with one of the countless antivirus live CDs. Also give Windows System Sweeper (which isn't on the list in the first link) a try. It's a version of Microsoft Security Essential 2 that can be burned to CD/DVD or copied over to a bootable thumb drive.

Windows is back in business (we hope!)

Hopefully one or more of these tips has gotten your machine back in business. Any more suggestions you like to share? Your machine won't boot up and all these steps didn't help? Let me know in the comments section below!

Now read this: 15 incredibly useful (and free) Microsoft tools for IT pros

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