Safe Mode is a version of your operating system in which all unnecessary files and programs are not loaded. Only the core system files are loaded, allowing for troubleshooting and repair.
When you are having problems with software on your computer the most useful way to diagnose and repair problems is to boot your computer into safe mode. Safe Mode is a special way for Windows to load when there is a system-critical problem that interferes with the normal operation of Windows. The purpose of Safe Mode is to allow you to troubleshoot Windows and try to determine what is causing it to not function correctly. Once you have corrected the problem, then you can reboot and Windows will load normally.
This is also the first step to remove any malicious software.
While the computer is starting up you must hit the F8 key. This should bring up a black screen displaying the advanced boot options that looks like this:
This will boot the computer into safe mode and allow you to have access to the internet. Once the computer is booted into safe mode you can diagnose issues with Windows or install and run anti-malware software without interference.