Safe mode is a troubleshooting option for Windows that starts your computer in a limited state. Only the basic files and drivers necessary to run Windows are started. The words Safe Mode appear in the corners of your monitor to identify which Windows mode you're using.
If an existing problem doesn't reappear when you start in safe mode, you can eliminate the default settings and basic device drivers as possible causes. If you don't know the cause of the problem, you can use the process of elimination to help you find the problem. Try starting all of the programs you commonly use, including the programs in your Startup folder, one by one to see if a program might be the cause of the problem.