Clean boot is useful when your Windows PC starts and runs properly only in Safe Mode. In such a case, most probably some third-party software or driver causes instability, and you can use the clean boot mode for analyzing the crash causes, or installing, updating, or removing software and drivers. This option might also be helpful in troubleshooting recurring performance problems.
As the very first sentence states, you should always try Safe Mode before turning on the clean boot. You can also enable clean boot from Safe Mode if Windows does not start in normal mode.
Because many third-party security programs do not start in clean boot mode, it is strongly recommended to run a full anti-virus scan before using this troubleshooting method.
The easiest way to start is to use the keyboard shortcut Windows Key+R to open the Run dialog, type msconfig, and click OK.
In Windows Vista, 7, and 10, you can also open the Start menu, type msconfig, and click the result.
In Windows 8 and 8.1, open the Start screen, type msconfig, and click the result. Note that in Windows 8.1 the results appear under the search box, not on the left side of the screen.
System Configuration Utility opens. First, click the Services tab on the top and then tick the Hide all Microsoft services check box. This makes sure you do not accidentally disable essential Windows services.
Then click the Disable all button on the bottom right to turn off all third-party services.
Move on to the Startup tab. In Windows XP, Vista, and 7, just click Disable all on the bottom right. Clean boot mode will be enabled after clicking OK and restarting your computer.
Since Windows 8, startup programs can be managed using Task Manager. That's why the Startup tab of System Configuration/msconfig is almost empty here.
Click the Open Task Manager link.
This opens the Task Manager's Startup tab in Windows 8, 8.1, and 10. Sadly, there is no Disable all button, so you must right-click or tap and hold each item in the list and choose Disable.
Close Task Manager after disabling all startup programs, and click OK to close System Configuration/msconfig.
In all versions of Windows, the System Configuration tool reminds you that you need to restart your computer to apply these changes. Click Restart to enable clean boot mode.
First, log in and let your computer run for at least a few hours to verify no crashes occur.
In Windows XP, a reminder of using System Configuration Utility pops up each time after logging in - to disable this, tick the check box and click OK.
After this, you can use free WhoCrashed for finding out the causes of the so-called BSoD-s (Blue Screen of Death). That is, if your computer actually displayed such screens, or rebooted by itself.
You can also install, update, or uninstall any software or drivers that might be the cause for system instability. Safe Mode allows managing only items that do not use Windows Installer.
Please note that not all software runs properly after disabling third-party services and startup items. This is expected behavior in clean boot mode.
Running System File Checker (SFC) at least twice to verify that all required system files are intact is also a good idea.
To fully troubleshoot the problem, you can use the System Configuration utility to turn disabled services and/or startup items back on one at a time, restarting your PC after each change. This helps in detecting the conflicting software that needs to be then uninstalled or updated/upgraded.
This is a time-consuming task, but it is often better than backing everything up and reinstalling Windows from the scratch.
After you've resolved the stability problems, it is time to turn off the clean boot mode.
Run System Configuration utility/msconfig and choose Normal startup from the General tab.
Revisit Services and Startup tabs to make sure that all items really have been turned back on. Sometimes, you do need to use the Enable all buttons despite choosing Normal startup.
Click OK to close msconfig and restart your computer to verify that everything works fine.
In case clean boot did not help
If clean boot mode fails to identify or resolve the source of problems, you can:
- Use System Restore to revert to a previous state when Windows was still working properly.
- Try the non-destructive reinstall of Windows XP, Non-destructive reinstall of Windows Vista or 7, or Non-destructive reinstall of Windows 8, 8.1 or 10, depending on the installed version of Windows.
- Leave clean boot mode on if Windows and third-party software work properly this way.