Many times in order to remove a piece of spyware or for troubleshooting and diagnostic purposes, you'll have to start Windows in Safe Mode. While in Safe Mode, only specific programs and files needed to run the operating system are loaded. Some functions, such as connecting to the Internet, will not be active in Safe Mode and a standard video driver will be loaded causing a washed out look and a possible change in resolution.
However, because just the essential programs and files are loaded in Safe Mode, this allows us to remove some spyware, adware, viruses and such that cannot be removed in Normal Mode. Follow the instructions below to Start Safe Mode for your specific version of Windows. If you are trying to delete a file that is not allowing you to delete it (even in Safe Mode), you may want to read my article on How to Delete an Undeletable File.
Included at the bottom of the article are instructions for starting Windows Vista in Safe Mode too.
Windows 95
Restart the computer.
Just after the POST diagnostics and memory count, start pressing the F8 key
On the Startup Menu, choose Safe Mode
Windows 98/Me
Restart the computer.
Just after the POST diagnostics and memory count, start pressing the F8 key
On the Startup Menu, choose Safe Mode
or you may use the System Configuration Utility Method.
While in Normal mode, Close all programs.
Click Start, Run and type MSCONFIG in the box and click OK
In the System Configuration Utility, on the General Tab, click the Advanced Button
In the Advanced Troubleshooting Settings dialog box, check Enable Startup Menu. Click OK. Click OK again when the System Configuration Utility reappears.
You will be prompted to restart the computer. Click Yes. The computer will restart in Safe mode.
When you are finished with troubleshooting in Safe mode, open MSCONFIG again and uncheck "Enable Start-up Menu." under the Advanced Menu, then click OK and restart your computer
Windows 2000
If the computer is running, shut down Windows, and then turn off the power
Wait 30 seconds, and then turn the computer on.
When you see the black-and-white Starting Windows bar at the bottom of the screen, start tapping the F8 key. The Windows 2000 Advanced Options Menu appears.
Ensure that the Safe mode option is selected. In most cases, it is the first item in the list and is selected by default.
Press Enter. The computer then begins to start in Safe mode.
When you are finished with all troubleshooting, close all programs and restart the computer as you normally would.
Windows XP
If Windows XP is the only operating system installed on your computer, booting into Safe Mode with these instructions.
If the computer is running, shut down Windows, and then turn off the power
Wait 30 seconds, and then turn the computer on.
Start tapping the F8 key. The Windows Advanced Options Menu appears. If you begin tapping the F8 key too soon, some computers display a "keyboard error" message. To resolve this, restart the computer and try again.
Ensure that the Safe mode option is selected.
Press Enter. The computer then begins to start in Safe mode.
When you are finished with all troubleshooting, close all programs and restart the computer as you normally would.
To use the System Configuration Utility method
Close all open programs.
Click Start, Run and type MSCONFIG in the box and click OK
The System Configuration Utility appears, On the BOOT.INI tab, Check the "/SAFEBOOT" option, and then click OK and Restart your computer when prompted.
The computer restarts in Safe mode.
Perform the troubleshooting steps for which you are using Safe Mode.
When you are finished with troubleshooting in Safe mode, open MSCONFIG again, on the BOOT.INI tab, uncheck "/SAFEBOOT" and click OK to restart your computer
Windows as part of a multiboot system
Use this method ONLY if you have multiple operating systems installed on your computer.
If the computer is running, shut down Windows, and then turn off the power
Wait 30 seconds, and then turn the computer on.
When the Boot loader menu (list of the available operating systems) appears, use the arrow keys on the keyboard to select the version Windows what you want
Press Enter, and then immediately begin tapping the F8 key. The Windows Advanced Options menu appears.
Scroll to and select the Safe mode menu item, and then press Enter.
Windows Vista
Windows Vista is similar to Windows XP for starting in Safe Mode.
Turn the computer on or Restart the computer
Start tapping the F8 key. The Windows Advanced Boot Options Menu appears. If you begin tapping the F8 key too soon, some computers display a "keyboard error" message. To resolve this, restart the computer and try again.
Ensure that the Safe mode option is selected (the top option)
Press Enter. The computer then begins to start in Safe mode.
When you are finished with troubleshooting, close all programs and restart the computer as you normally would.
Source: pchell.com