There's some piece of utter stupidity built in to Win10 which, by default, tries to re-open any programs which were running when you turned off the computer...
So if a problematic website caused the problem (usually caused by one of the plethora of poorly reviewed adverts) and you had to turn off the computer via the power switchthen , if you restart the computer, Win10 will re-open the website and may freeze the computer again.
So you have to remember to deactivate Internet connections first, which can mean turning off the router if you're unlucky enough not to have a hardware switch, then re-boot, then close the browser program, then restart the router!
Fortunately it's possible to disable this irritating geekery by going to 'settings', then 'accounts', then 'sign-in options', scroll down to 'privacy' and make sure that the second item is turned off.