It is a common scam.
Tech Support Scamming through unsolicited phone calls, browser pop-ups and emails (aka Tech Support Scamming) from "so-called Support Techs" advising "your computer is infected with malware", “All Your Files Are Encrypted" and other fake "alert messages" has become an increasing common scam tactic over the past several years. The scams may involve web pages with screenshots of fake Microsoft (Windows) Support messages, fake reports of suspicious activity, fake warnings of malware found on your computer, fake ransomware and fake BSODs all of which include a tech support phone number to call in order to fix the problem. If you call the phone number (or they called you), scammers will talk their victims into allowing them remote control access of the computer so they can install a Remote Access Trojan in order to steal passwords and other sensitive personal information which could then be used to access bank accounts or steal a person's identity.
These are a few examples.
The scammer may claim to be affiliated with Microsoft or Windows Support. However, there have been reports of scammers claiming to be affiliated with major computer manufacturers such as Hewlett Packard, Lenovo and Dell, familiar security vendors like Symantec, Panda, McAfee, etc. and even popular ISPs.
Microsoft does not contact users via web page messages, phone or email and instruct them to call tech support to fix your computer.
Not answering any questions and hanging up the telephone is the best way to deal with phone scammers...then report them to the appropriate authorities.
If you are dealing with browser pop-up scams, closing the web browser and then relaunching it usually eliminates the bogus warning message and is the best way to deal with these scams. If the browser freezes or hangs, you may have to close it with Windows Task Manager by selecting End Task.
Scammers and cyber-criminals are very innovated...see Tech Support Scams use new Tricks to Hold Browsers Hostage. They are always developing creative and more sophisticated techniques to scare their victims into providing personal information or stealing their money for financial gain. The criminals can target specific browsers like Microsoft Edge, Google Chrome, specific devices like Apple and even your iPhone or iPad.
Some scam sites may lock up the browser, load the page in full-screen mode or spawn an infinite loop of repeating fake alert dialog boxes that prevent the victim from closing it or navigating away. Despite years of warnings by experts not to click on anything, such behavior requires victims to click OK or similar prompt on the fake alert message if using Dialog Loop Protection supported browsers like Microsoft Edge in order to escape or close the page. Google Chrome has a feature to "Prevent this page from displaying additional dialogs". Some Tech Support scams have similar alerts while others are simply made up and clicking OK can produce the opposite effect. If you are dealing with this type of scam, click the OK button at the bottom of the alert and you should then see a box that says "Do not allow this site to create new pages". Check that box and close the window.
For more information about how these scams work and resources to protect yourself, please read Beware of Phony Emails & Tech Support Scams...there are suggestions near the bottom for dealing with scams and a list of security scanning tools to use in case the usual methods do not resolve the problem or you allowed remote access into your computer.