A full-screen warning appears: "Your computer is infected! Call Microsoft Support now!" with a loud alarm and a phone number. Take a breath, it is a scam, and your computer is almost certainly fine.

How it works

These pages are designed to scare you into calling. The "technician" who answers will ask for remote access and a payment to "fix" a problem that does not exist — and may actually install something harmful in the process.

What to do

• Do NOT call the number or let anyone remote in.
• Close the browser. If it will not close, restart the computer.
• Real companies never put a phone number in a pop-up.

If you already called

If you let someone in or paid, change your passwords and call your bank. Then have the machine checked and cleaned. We do that remotely and can secure your accounts so it does not happen again.