Practical Uses for Safe Mode
If you are unable to start your system by using Last Known Good Configuration, Windows XP Professional, Windows 2000 and Windows Server 2003 provides safe mode, a startup option that disables startup programs and nonessential services to create an environment useful for troubleshooting and diagnosing problems. In safe mode, Windows XP/2000/2003 starts a minimal set of drivers that the operating system needs to function. Support for devices such as audio devices, most USB devices, and IEEE 1394 devices is disabled to reduce the variables that you need to account for when diagnosing the cause of startup problems, Stop messages, or system instability.
Logging on to the computer in safe mode does not update Last Known Good Configuration information. Therefore, if you log on to your computer in safe mode and then decide you want to try Last Known Good Configuration, the option to do so is still available.
Essential drivers and system services enabled in safe mode include the following:
- Drivers for serial or PS/2 mouse devices, standard keyboards, hard disks, CD-ROM drives, and standard VGA devices. Your system firmware must support universal serial bus (USB) mouse and USB keyboard devices in order for you to use these input devices in safe mode.
- System services for the Event Log, Plug and Play, remote procedure calls (RPCs), and Logical Disk Manager.
Enabling only components needed for basic functionality allows the operating system to start in the following situations:
- The computer consistently stops responding: You can restart the operating system in safe mode and use the tools described in this appendix to diagnose and resolve problems.
- The computer starts with a blank or distorted video display: You can start your computer in safe mode and then use Control Panel to select video adapter settings that are compatible with your monitor. New settings take effect when you restart the computer.
- The computer does not start normally after you install new hardware or software: If recently installed hardware or software prevents you from starting Windows XP Professional in normal mode, you can use safe mode to uninstall software, or to remove or roll back device drivers.
- The computer is infected with virus or Trojan, which is residing in the system configuration. Since Windows use the files considering them as essential part of the normal system configuration, you are not able to clean or get rid of them. The files and drivers that are considered “in use” by operating system are blocked from any accidental or intentional modifications. So, Many forms of malicious software will protect or reinstall themselves constantly if they are allowed to start in the first place. These programs will situate themselves in one of the many autorun locations in the Windows registry and file structure. When Windows is started normally, so is the offending software, running as a process in the background. When you start the PC in Safe Mode, these autorun locations are not used, and no software is started automatically. This can allow virus and spyware removal programs the opportunity they need to remove the malicious software completely. If you are having virus or spyware problems on your PC, you should always run antivirus and anti-spyware programs in Safe Mode to ensure that they have maximum effect.
There are circumstances where safe mode will not be able to help you, such as when Windows system files that are required to start the system are corrupted or damaged. In this case, the Recovery Console may help you.
Safe Mode also bypasses startup programs. Bypassing startup programs reduces system complexity and enables you to see whether a startup program is the source of the problem.
In safe mode, the operating system does not run network-based startup programs. To enable network logon scripts in safe mode, select Safe Mode with Networking on the Windows Advanced Options Menu.
How to start your computer in safe mode
- Remove all floppy disks and CDs from your computer, and then restart your computer.
- When prompted, press F8. If Windows XP Professional starts without displaying the Please select the operating system to start menu, restart your computer. Press F8 after the firmware POST process completes, but before Windows displays graphical output.
- From the Windows Advanced Options Menu, select a safe mode option listed in the following list:
- Safe Mode (SAFEBOOT_OPTION=Minimal): This option uses a minimal set of device drivers and services to start Windows.
- Safe Mode with Networking (SAFEBOOT_OPTION=Network): This option uses a minimal set of device drivers and services to start Windows together with the drivers that you must have to load networking.
- Safe Mode with Command Prompt (SAFEBOOT_OPTION=Minimal(AlternateShell)): This option is the same as Safe mode, except that Cmd.exe starts instead of Windows Explorer.
- Enable VGA Mode: This option starts Windows in 640 x 480 mode by using the current video driver (not Vga.sys). This mode is useful if the display is configured for a setting that the monitor cannot display.
Note Safe mode and Safe mode with Networking load the Vga.sys driver instead.
- Last Known Good Configuration: This option starts Windows by using the previous good configuration.
- Directory Service Restore Mode: This mode is valid only for Windows-based domain controllers. This mode performs a directory service repair.
- Debugging Mode: This option turns on debug mode in Windows. Debugging information can be sent across a serial cable to another computer that is running a debugger. This mode is configured to use COM2.
- Enable Boot Logging: This option turns on logging when the computer is started with any of the Safe Boot options except Last Known Good Configuration. The Boot Logging text is recorded in the Ntbtlog.txt file in the %SystemRoot% folder.
- Starts Windows Normally: This option starts Windows in its normal mode.
- Reboot: This option restarts the computer.
- Return to OS Choices Menu: On a computer that is configured to starting to more than one operating system, this option returns to the Boot menu.
If you only want to enter Safe Mode occasionally and have trouble using the F8 key, you can use the System Configuration Utility (msconfig). Go to Start|Run and enter “msconfig” (without quotes). When the utility opens, click on the tab BOOT.INI as shown in the figure below.
- Shut down the computer and allow it to restart
- By default, it will start in Normal Mode