Anyone with a Windows PC will recognise this message, Do you wish to turn on your computer in safe mode?
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Safe mode loads few executable modules and disables devices and drivers from third parties. Booting up in Safe Mode in Windows loads only Windows.

Safe mode exists to allows the user to access diagnostic programs for maintenance.

It can be used to locate particular problem software which is impacting device performance.

But ‘safe mode’ has moved far beyond the PC.

The server operating systems Windows, Unix, Linux, Ubuntu can all be operated in safe mode.
Mac OS has a safe mode.
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For hand held devices Android Safe Mode: To access safe mode power off your phone

Browsers also have a safe mode. In safe mode Internet Explorer runs without add ons

Starting Internet Explorer in ‘SafeMode
1. Open a ‘Command Prompt’ window.
2. Type cd/ to get a blank C: prompt.
3. Type in "C:Program FilesInternet Exploreriexplore.exe" -extoff (where C: is your local drive)
4. Press ENTER. (source Dell.com)

 

Method 1 Using the Firefox Menu
1. Open Mozilla Firefox. …
2. Click the Menu icon. …
3. Open Help. …
4. Click Restart with Add-ons disabled. …
5. Click Continue in Safe Mode. …
6. Disable add-ons one by one. …
7. Reset Firefox completely if nothing else works.

Source – http://www.wikihow.com/Start-Firefox-in-Safe-Mode – with pictures

To run Google Chrome in ‘safe mode’ see

http://techhelpbuzz.com/browser/google-chrome/how-to-run-google-chrome-in-safe-mode-or-incognito-mode/