Windows Safe Mode

What is it?

Windows Safe Mode is a diagnostic mode of the Windows OS. As far as I can tell, it's been around since at least Windows 3.0.

Safe Mode generally acts like a regular booted up version of Windows, except many non-core functions are disabled. Only basic files and drivers needed to run Windows are loaded. This is useful since this is a relatively short list of functions (see all the text flying on the screen while safe mode boots), which often excludes malware and other troublesome programs. From there, you can use Safe Mode as a way to facilitate a process of elimination for solving your problem.

Accessing Safe Mode is done by pressing the F8 key while Windows is booting --right before the OS's logo shows up-- and choosing one of the three Safe Mode options from the menu. It's OK to basically just mash F8 from when you turn the PC on until something happens...

From here, a handful of options will be available to you from the Windows Advanced Options Menu (this list will vary sometimes depending on the OS and how the OS was installed). Note that this is NOT a boot menu. 

What to use it for

How you use Safe Mode is largely determined by what you're trying to accomplish.

If the computer is infected with malware that is preventing the usage of Malwarebytes or System Restore:

1. Safe Mode may restore this functionality well enough to clean up the computer, either with Malwarebytes, Sophos, or perhaps manually.

If the PC has become notoriously unstable but is able to boot into Safe Mode, there are a couple things you can try:

1. Restart. Plain and simple. Letting Windows shut down normally from Safe Mode may fix the problem.
2. Investigate the cause of the Blue Screen. You now know one thing for sure: Whatever is causing the fatal error is NOT related to a core Windows process. This means that the questionable program may be able to be removed while in Safe Mode. 
3. Back up Data. If all else fails, you can use Safe Mode to gain access to the hard drive and move or email important files to another hard drive. If it's come to this, you're probably about to just re-install Windows. 

The Windows Advanced Options Menu

Section 1

1. Safe Mode - This boots up the "regular" version of safe mode. Networking is disabled and only basic graphic and interface drivers are loaded.

2. Safe Mode with Networking - Same as regular Safe Mode, except the wireless card driver and settings are loaded, too.

3. Safe Mode with Command Prompt - Same as regular Safe Mode, except the boot process will stop just before the GUI and will instead just starts the command prompt (cmd.exe).

Section 2

1. Enable Boot Logging - Creates a file, ntbtlog.txt, that lists all the drivers that are installed and start during start-up. Might be useful for advanced troubleshooting. The file is saved at the root of C:\

2. Enable VGA Mode - Starts Windows using your current video driver and low resolution and refresh rate settings, basically something that any monitor should be able to display. You can use this mode to reset your display settings in case you messed something up and can't see anything anymore...

3. Last Known Good Configuration - God send. This simply boots Windows with the same driver and registry settings it had the last time it successfully made it to the Desktop. Very useful against malware that messes with the Registry, but not as good as System Restore. Note that the issue that caused the computer to stop booting may still be at large.

4. Directory Services Restore Mode - Used only by a Windows machine that hosts an Active Directory. Starts Windows domain controller running Active Directory so that the directory service can be restored. 

5. Debugging Mode - Used to improve error reporting, usually while debugging software.

6. Disable Automatic Restart on System Failure - Prevents Windows from automatically rebooting whenever it Blue Screens. So, you know, you can actually read what the Blue Screen was caused from. Useful when a machine fails to boot consistantly. 

Section 3 (And options not listed in the above image)

1. Start Windows Normally -  For when you didn't mean to bring up this menu.

2. Reboot - For when you have no idea what you're doing (Hey, bring up this menu alone was kinda cool, right?)

3. Return to OS Choices menu - If there are multiple OSs installed on this hard drive, this will let you go back to the list of OSs and maybe choose to boot into a different OS. This option usually only appears when there are multiple Windows OSs installed (Installing UNIX OSs usually installs GRUB as the default unified boot loader).

4. Repair -This option started to appear in Windows Vista and later. This will boot into a special version of Windows that shows a list of system recovery tools you can use to repair start-up problems, run diagnostics, or run System Restore. This option is available only if the tools are installed on the computer first... most likely by the manufacturer. If it's not there, you can install the system recovery tools from a Windows Installation disc... though that's probably not very useful if the computer already has a problem.