A very common scam going around now is what we call “scareware”. Your computer screen will freeze up with an official looking warning saying your computer is at risk and you need to call Microsoft.
Sometimes they actually call your phone and claim to be Microsoft warning you about a risk with your computer.
They will try to talk you through with some tech-tricks (event logs and registry edits) to convince you to let them access your computer.
Don’t do it! Hang up and call us to assess your risk! Microsoft will never call you! But we can help you.