Recently I have talked to a number of clients who have gotten a call from Microsoft telling them that they detected some kind of problem with their computer that needs to be repaired. They then try to get you to go to a website so they can remote into the computer and help you fix it.
This is a scam. Microsoft will never cold call you. The person/company claiming to be Microsoft wants to remote in, create an issue and expect payment to fix it. If you get one of these calls, tell them not to call back and hang up!
You can read more about it in this Microsoft announcement: