A user should enter Safe Mode when troubleshooting a Windows system. When in Safe Mode, a system is only running basic files and drivers necessary to run Windows.
When a system fails to run properly, it may be after-market programs or device drivers causing the issue. Starting a computer in Safe Mode allows a user to see if the existing problem arises in Safe Mode, and if not, tells the user the problem is not with the basic device drivers or default settings.
Safe Mode is meant as a process of elimination when it comes to diagnosing a problem. If a system automatically boots into Safe Mode without prompting, it means something is keeping Windows from starting normally.