When you run a computer in safe mode, you can start it, test most of its systems, and change certain settings. Safe mode is an excellent way to diagnose — and often fix — your computer’s problems.
Start your computer in safe mode
If you can start your PC in safe mode, its basic hardware probably isn’t the cause of your problem. If you can’t start your PC in safe mode, you have a problem with basic hardware or the basic elements of Windows. If your PC starts in safe mode all by itself, some component is preventing normal startup.
Remove any discs from the CD/DVD drive, if your PC has one and shut down your computer.
If you can’t do a normal shutdown, press the Ctrl+Alt+Del key combination and then release the keys. Next, press and release the Alt key; press the U key to select the Shut Down menu; and press the U key to turn off the computer. (This works in XP, but not in Vista or Windows 7.)
Wait a few moments to allow the computer to shut off fully; then restart.
The computer begins processing its self-test, and you should be able to see messages on the screen, including advice on alternative ways to start the computer.
When the self-test is complete and the computer pauses before it begins loading Windows, repeatedly press and release the F8 function key on the keyboard.
Keep doing so until the Windows Advanced Options Menu screen appears.
If you begin tapping the F8 key too soon, you’ll see a “keyboard error” message; restart the computer and try again. If you begin tapping too late, the computer will go on to load Windows, and you have to repeat the shutdown/startup process.
Use the arrow keys to select the version of Windows you want to start in safe mode and then press F8; otherwise, press the arrow keys on the keyboard to highlight the Safe Mode option and press Enter.
The computer starts loading Windows in safe mode. When Windows is fully loaded in safe mode, you see the words Safe Mode in the corners of your screen. To exit safe mode, simply restart the computer from the Start menu and allow Windows to load normally.
Use your computer's safe mode tools
When you’ve restarted a troublesome computer in safe mode, you can use several diagnostic and repair tools to attempt a fix.
Plug and play: The availability of plug and play means that the computer can recognize most devices that are plugged in during or after start-up. Not all device drivers are available in safe mode, however.
Help and Support: Choose Start→Help and Support to open the Help and Support window, which provides searchable instructions and troubleshooting tips for many elements of the system. In basic safe mode, however, networking and Internet access are disabled; to search on the Web for assistance, you have to choose the Safe Mode with Networking option during start-up.
Device Manager: This tool allows you to update device drivers and configure hardware.
System Restore: This utility lets you retrieve settings and other information stored in the computer at an earlier time.
Command prompt: In certain circumstances, you may want to reach the command prompt to run a program that resides outside Windows. To display the prompt, choose Start→All Programs→Accessories-- >Command Prompt.
Registry Editor: This tool is not for inexperienced or unguided users. You may need to use it, however, if a support professional directs you to make changes in your Windows Registry files.
Don’t make changes without backing up the previous set of files and without getting specific instructions about changes. A mistake in a critical section can render Windows unusable, requiring you to reinstall it.
Test new computer hardware in safe mode
You can test new hardware in safe mode. Start your computer in safe mode. Uninstall any drivers or other software that you installed for the new hardware. Then shut down your computer, uninstall the new hardware, and restart the computer in normal mode.
If the problem goes away, you’ve isolated its source. Contact the manufacturer of the new hardware for assistance.