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14-10-2004, 05:26 PM
FAQ #31 - What is safe mode? How do I restart in safe mode?

Originally written by Elwin Way


What is Safe Mode?

Safe mode is a component of Windows that loads the bare minimum device drivers to get your computer working and does not load drivers and programs that are normally loaded at startup, eg anti-virus programs, utilities, ICQ, etc.

Sometimes Windows will boot into safe mode after installing new hardware or software. Safe mode will also start up automatically if Windows does not boot on the previous attempt.

You can manually invoke safe mode by pressing F5 or by pressing F8 and selecting it from the boot menu.


Why boot into safe mode?

Safe mode is a powerful troubleshooting tool used to solve many different types of computer problems including conflicts, hardware and software problems, cleaning out viruses, trojans and other pests as well as to perform hard drive maintenance, eg scandisk and defragmenting.

A troubleshooting example may be a new piece of hardware may conflict with an existing one, eg when upgrading your sound card you may find that it conflicts with the modem.

By going into safe mode, you can open up System Properties and check for conflicts, or you can check for device driver problems etc. Because safe mode does not load the normal hardware drivers, driver conflicts are usually eliminated enabling Windows to run and the problem to be repaired. Note that you will also have limited functions eg no CD drive and add-on cards may not work.

Alternatively, if your computer boots into safe mode after installing a new program, the problem may lie with the new program preventing Windows from starting normally. You may safely uninstall or setup the new program in safe mode.

Sometimes you may want to get into safe mode manually in order to change a setting or remove/update a driver while it is not loaded.

Another reason is to perform system maintenance like running scandisk and defrag while the system is 'free' of running tasks. Note: The Windows screensaver is not disabled in safe mode. If you are using safe mode to run scandisk and/or defragment your hard drive you will still need to disable your screensaver.

Safe mode is useful if your monitor settings have been altered and the monitor displays a picture as if the horizontal hold is lost, eg if the highest monitor resolution is only 800*600 and someone tries to display 1024*576, the display will display a setting as if the horizontal hold is lost. Just reboot to safe mode and put the settings back to 800*600.
-- contributed by E.ric


How is safe mode different to a normal boot?

There are several things that happen when Windows boots into safe mode that differ from a standard boot:

• Safe Mode does not run the autoexec.bat or config.sys files.

• Most device drivers are not loaded. A device driver is the software that Windows uses to interact with a piece of hardware, such as a printer or scanner.

• Himem.sys, which is normally loaded as part of the config.sys script, is loaded with the /testmem:on switch. This switch tells the computer to test the extended memory before continuing.

• Safe mode checks the msdos.sys file for information on where to find the rest of the Windows files. If it finds the files, it proceeds to load Windows in safe mode with the command win /d:m. If it does not find the Windows files, it will run command.com to bring up a C: prompt.

• Windows boots using a batch file called system.cb instead of the standard system.ini file. This file loads the Virtual Device Drivers (VxDs) that Windows uses to communicate with the standard parts of the computer.

• Windows now loads the regular system.ini file plus win.ini and Registry settings. It skips the (except for the shell and device lines) and [386Enh] sections of system.ini and does not load or run any programs listed in win.ini.

• Because drivers and programs are not loaded, instead of the normal graphics device driver safe mode uses standard VGA graphics mode which is supported by all Windows-compatible video cards. This means that the Windows desktop loads up in 16 colors and at a resolution of 640 x 480 with the words "safe mode" in each corner.


[b]To start Windows in Safe mode:

1. Start Windows, or if it is running, shut Windows down and turn off the computer.

2. Wait 30 seconds then restart the computer. The computer begins processing a set of instructions known as the Basic Input/Output System (BIOS). What is displayed depends on the BIOS manufacturer. Some computers display a progress bar that refers to the word BIOS while others may not display any indication that this process is happening.

3. As soon as the BIOS has finished loading, begin tapping the F8 key on your keyboard. Continue to do so until the Windows Advanced Options menu appears.

NOTE: If you begin tapping the F8 key too soon, some computers will generate a "keyboard error" message. Please restart and try again.

4. Using the arrow keys on the keyboard, scroll to and select the Safe Mode menu item, and then press Enter.

NOTES:

• On some computers, this can be quite difficult. If you are not successful and the computer starts in normal mode, try again.

• Note also that how (or even if) you can boot into safe mode may depend on the version(s) of Windows and the boot setup that you use.

For example I have dual boot Windows XP and Windows 98 and have some trouble (not necessarily insuperable) getting the Windows 98 into safe mode. Holding down F5 or F8 or CTRL during the boot does NOT work.
-- contributed by Rugila

• On some motherboards (like this one Asus P4P800), you have to press F8 twice. As F8 on this mobo also brings up a window, where u can select a device you want to boot from (if you press F8 after post).

And then press F8 again, before the XP logo appears.

So, yup it also depends on the mobo, on whether you press F8 once or twice, before you can get into safe mode.
--contributed by Spacemannz

• A lot of systems, but not all, will boot into safe mode by holding down the Shift key while booting the computer after the BIOS screen. With some computers you cannot see the BIOS screen so hold down shift and if the computer halts then release the Shift key for a second, then hold down the Shift key again.
-- contributed by tweak'e

• For Windows XP Home you will need to choose the Administrator's account in order to boot into safe mode.


Alternative method (Windows XP only):

The preceding methods may be difficult on some extremely fast computers. This is an alternative to start Windows in safe mode:

1. Click on Start, and then click Run.
2. Type msconfig and then click OK.
3. Click the Boot.ini tab.
4. In the Boot Options section, check the /SAFEBOOT.
5. Click OK to save your changes and restart the computer.

When you have finished troubleshooting the problem, repeat the procedure and uncheck / SAFEBOOT.


Alternative method (Windows 98/ME):

1. Click on Start, and then click Run.
2. Type msconfig and then click OK.
3. Under the Advanced button option you can enable the Startup menu whereby you can pick which option you need.

This saves pressing F8 or holding Shift each time you want to get into safe mode and is handy for trouble shooting. TweakUI has a similer option as well.
-- contributed by tweak'e


Additional information

There are three types of safe mode that are available in some versions of Windows. In most cases you should select the Safe Mode menu item unless you are instructed otherwise. The following is an explanation of the three types of safe mode that you see on the menu:

Safe Mode:
Windows will start in safe mode. The Windows interface will be somewhat different; menus and icons will be larger and may be in different locations. You will not have access to the internet or a network.

Safe Mode with Networking:
Windows will start in safe mode as mentioned above. In addition, network drivers will be loaded, and you should have network access. You may have internet access if you access it across a network instead of a dial-up connection.

Safe Mode with Command Prompt:
Windows will start in safe mode with a black MS-DOS screen. No Windows interface is displayed and network drivers are not loaded.


More information about safe mode can also be found at the Beginners Guides: Windows XP Safe Mode Explained (http://www.pcstats.com/articleview.cfm?articleID=1643).



Original FAQ available from here (http://pressf1.pcworld.co.nz/thread.jsp?forum=1&thread=21833&message=58781&q=safe+mode#58781).