Safe mode tells you one thing best: whether the problem you are trying to troubleshoot is with Windows. In Safe mode, only Windows itself is loaded: the basic parts of the operating system. Any other software — including device drivers, start-up processes, and other programs — aren’t loaded in Safe mode. This leads to one immediate, solid conclusion:

When the computer runs fine in Safe mode, the problem you have is not caused by Windows.

Also, when the computer performs flawlessly in Safe mode, the problem is also not caused by your computer hardware. No, the problem lies in some program being loaded after Windows itself starts.

Your job in Safe mode is to determine which piece of software is causing the problem and to either update that software or disable it to keep the computer running properly.

  • When the problem persists in Safe mode, it’s most likely a Windows issue.

  • In some circumstances, Windows doesn’t cause a problem that continues in Safe mode. These problems are hardware related. The most common one is overheating. Check the power supply. Other hardware may also be screwing up.

If your PC starts itself in Safe mode, odds are very good that the problem is caused by one of three things:

These three areas are known as the problem sisters. The problem most likely lies with the software — the device driver — used to control the specific hardware. Especially if you recently upgraded the hardware or software in any of these three areas, problems can occur that thrust the PC into Safe mode.

The first thing to try is waiting. Just let the computer sit. Or, if possible, try to re-create the situation that caused the computer to crash. If the action can be repeated in Safe mode, the problem lies with Windows, not with the device.

The second thing to try depends on what happened recently. If you recently updated software, run System Restore to return the computer to a point before the update.

Finally, check for new software. Use the Device Manager. If there’s known trouble with the device, its Properties dialog box in the Device Manager tells you so. If not, click the Update Driver button to find a new driver. Also consider contacting the hardware manufacturer to see whether an update is available. (You have to use Safe mode with Networking to access the Internet in Safe mode.).