Never call 1-800-363-4991:
You need to be aware that your PC is infected with a pesky adware when you are browsing any website, a new tab will up and start redirecting at least 3 times to a random website with a WINDOWS FIREWALL WARNING!" screen after every click. Sometimes the URL addresses are different, and the screens often are too, but it's all one problem caused by a tech scam adware as the number displayed seems to be the same: 1-800-363-4991. Here is one example of warnings page:
