How to Use Safe Mode to Diagnose a PC Problem

Is Windows misbehaving? One diagnostic technique you can try is Safe Mode to see if you can narrow down the cause of the trouble. Here's how to start Windows 10 in safe mode.

Is your Windows machine freezing, crashing, or just not up to snuff? It could be a bad application, a quirky driver, or even a faulty piece of hardware.

One way to get to the bottom of the problem is by starting the OS in Safe Mode, which launches Windows in a clean, pristine, barebones fashion by preventing certain drivers and other features from running. If Windows works happily in Safe Mode, it typically means the fault lies within a certain driver, service, or other item that would otherwise load.

The steps offered here assume that you can at least boot into Windows and access the Safe Mode feature.

How to Start Windows 10 in Safe Mode

In the search field, type the command msconfig. At the top of the search results, click on the entry for System Configuration.

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The System Configuration window appears. Your current setting is most likely Normal Startup or Selective Startup. Click on the second option for Diagnostic startup, which loads only basic drivers and services. Click OK and reboot Windows.

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After Windows restarts, try to reproduce the problem you were experiencing. Whether or not the trouble has disappeared, you'll still need to run further testing to attempt to narrow it down. Open the System Configuration tool again and click on the Boot tab and the checkbox for Safe boot.

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Then try the different options, such as Minimal, Alternate shell, and network, rebooting with each selection. With each reboot, try to reproduce the original problem. If the problem goes away, then try booting into Normal mode and see if the problem is really gone.

Otherwise, move on to one of the other options. You can also try clicking on each of the different checkmarks to the right—No GUI boot, Boot log, Base video, OS boot information. Reboot the PC with each option checked one by one and see if the problem is gone or is still around.

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You can also check the Services tab. There are probably a lot of services listed here, but you can click on or off the checkmark for each service one by one and see if the problem might be related to a specific service.

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At this point, if you can narrow down the problem to a specific driver or service, you can run a Google or Bing search for that item to see if other people are bumping into trouble with it and how they may have resolved the issue.

Windows 10 and 8.1

If you're running Windows 10 or 8.1, you have other options for booting into Safe Mode. In Windows 10, click on the Start button > Settings > Update & security > Recovery. In the Advanced Startup section, click on the button to Restart now.

In Windows 8.1, launch the Charms bar, then click on the Settings charm > Change PC Settings > Update & recovery > Recovery. In the Advanced Startup section, click on the button to Restart now. Under Advanced startup, click on the button to "Restart now."

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At the "Choose an option" screen, click on the Troubleshoot button.

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At the Troubleshoot screen, click on the Advanced options button.

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At the Advanced options screen, click on the Startup Settings button.

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At the Startup Settings screen, click on the Restart button.

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At the next Startup Settings screen, press one of the keys from 1 through 9 to select a specific startup type, for example, 1 to Enable debugging, 4 to Enable Safe Mode, or 5 to Enable Safe Mode with Networking. Then click on the Restart button.

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Your PC will reboot with the startup type you selected. You can now once again try to reproduce the problem you've been experiencing in Windows to see if you can narrow it down.