If you noticed the computer is acting strange after installing new software or device drivers or your computer will not boot normally, booting to Safe Mode might help to get rid of the problem without starting the program in question. You can also often get rid of malware or spyware infection by running a scan in Safe Mode.
What if Safe Mode is not working in Windows?
If you tried to press the F8 key on your keyboard to hopefully boot the computer into Safe Mode, but it fails, you should try to allow the computer to boot normally. When the desktop has finished loading, open the System Configuration Utility in Windows to configure the system to start in Safe Mode:
Click on Start → Run → type MSCONFIG → press enter key on the keyboard. Select the Boot.ini tab (for XP) or Boot tab in Vista or Windows 7. Under Boot Options, select /SAFEBOOT (in XP) or put a check in the box for Safe Boot (for Vista and 7 users). Click OK and allow the system to restart when you received the prompt to restart the computer.
What if malware prevents MSCONFIG from running?
In some cases, malware prevents you in opening MSCONFIG; you can download Emergency Utilities to create usable copies of MSCONFIG, Regedit, and Task Manager from Doug Knox’s website. Use the MSCONFIG from that download to set up the PC to boot into Safe Mode. If this utility will not help to boot the computer in Safe Mode, malware like the Conficker worm might have deleted the registry key in Windows that will allow the computer to boot to Safe Mode. If that is the case, you should get rid of the malware by using an antivirus rescue CD e.g. AntiVir Rescue System, Sunbelt’s VIPRE Rescue, Panda SafeCD, etc.
Once the computer is malware-free, you can proceed to boot to Safe Mode to troubleshoot Windows but I suggest running the System File Checker Utility in Windows to replace or fix any damaged or deleted system files that a malware or buggy software and driver have caused on the system: Click on Start → Run → type cmd → press Enter key on the keyboard.
Note: Vista and Windows 7 users need to run the command prompt as admin. Click Start → All Programs → Accessories → right-click Command Prompt and select “Run as Administrator.” Then type cmd and press Enter.
In the Command prompt window, type SFC /scannow then press the enter key on the keyboard to allow SFC utility to scan the computer for any damaged or corrupted system files. If that helps and you’ve finished using Windows in Safe Mode, proceed to run the Windows Update program in Vista or Windows 7 or visit the Windows Update website to ensure that the replaced system files by SFC utility is patched.