July 20, 2026
"Your computer is infected!" What to do when a scary pop-up appears
You’re quietly reading an article when the screen suddenly fills up: "WARNING! Your computer is infected with 5 viruses", a countdown, sometimes a voice or a siren, and a toll-free number to call "immediately".
It’s frightening, and that’s the point. But here’s the good news: this isn’t your computer talking. It’s simply a web page — a dishonest ad — showing in your browser. It can’t see anything on your computer, and it hasn’t scanned a thing.
Three things you must not do
- Don’t call the number shown. On the other end it’s not Microsoft, not Apple, not your provider: it’s the person who made the fake alert.
- Don’t click the buttons in the window, not even "Close", "Cancel" or "Clean now". On this kind of page, every button leads to the same place.
- Don’t install anything, and don’t let anyone "take remote control" of your screen to help you.
The steps, calmly
- Don’t touch anything for ten seconds. Nothing is getting worse, and the countdown has no consequences.
- Close the browser tab using the small X on the tab itself, at the top of the window — not the buttons shown inside the page.
- If the tab won’t close, close the whole browser: on Windows, right-click its icon in the bar at the bottom, then "Close window". On Mac, open the browser’s menu at the top left and choose "Quit".
- If nothing budges, restart the computer. It’s completely safe and it makes the page disappear for good.
- Reopen your browser. If it offers to restore your previous pages, decline — otherwise the fake alert comes right back.
What if I already called or clicked?
It happens, and it isn’t foolish: these messages are built by professionals of fear. If you only spoke on the phone without installing anything or giving out information, hang up — it’s over.
If you let someone connect to your computer, or gave out a card number, act quickly: shut the computer down, call your financial institution to report the card, and have the device checked by someone you trust. Then change your email password from a different device.
You can also report the attempt to the Canadian Anti-Fraud Centre. And above all, talk about it: there’s no shame in being caught off guard by an alarm designed to panic you.
If the fake alert keeps coming back, an unwanted browser extension has usually installed itself — that can be fixed, but not by clicking at random. We travel to every Montreal neighbourhood for exactly this kind of clean-up, and we show you how to spot the next one while we’re there.
Frequently asked questions
How can I tell a real alert from a fake one?
A real antivirus never asks you to call a phone number, never shows a countdown and never plays an alarm sound. It shows a small, quiet notification in a corner of the screen. Phone number + urgency = fake alert, every time.
Should I buy an antivirus after this?
Not in a panic, and definitely not the one the window offers. Windows and macOS already include protection that’s perfectly adequate for everyday use at home, as long as you keep the device updated.
Want to go further?
We’ll walk you through all of this in person, at home, at your pace — and the first lesson is free. We travel across the island of Montreal, from the Plateau to Rivière-des-Prairies.
Book my free lesson