Why does my computer say Microsoft detected a virus?
It doesn't. That's a web page pretending to be a warning.
Microsoft never puts a phone number in an error message. Neither does Apple. Neither does any real security program. No operating system has ever asked you to call anyone. That one fact settles it, permanently.
Your computer is fine. Nothing is infected. The phone number is the only dangerous thing on that screen.
Make it go away right now
- Don't call the number.
- Close the browser window.
- If it won't close, force it: Ctrl + Alt + Delete (Windows) or Command + Option + Escape (Mac), select the browser, end it.
- If that fails, hold the power button until the computer turns off. This is safe. The message telling you not to shut down is lying — it says that only to keep you frightened and looking at the number.
- Turn it back on. Don't restore the old tabs.
Done. Nothing else is needed. No scan, no cleanup, no call.
Why it happened
You clicked an ad, probably on a perfectly ordinary website. Ad space gets sold and resold, and scammers buy it. The "warning" is just a web page — some text, a picture of a shield, sometimes a siren sound and a robotic voice. It can go full screen and it can pretend the mouse is stuck.
It's a photograph of an emergency, not an emergency.
Stop it happening again
- Install an ad blocker (uBlock Origin is free and well-regarded)
- Keep your browser updated
- Don't install "PC cleaner" or "driver updater" programs — that whole category is a problem
- Never call a number that appears on your screen. Not once.
What if I already called?
Then they walked you through installing a remote access program — AnyDesk, TeamViewer, LogMeIn, UltraViewer — and showed you something scary (usually Windows Event Viewer, which shows hundreds of harmless red "errors" on every computer on earth).
Go to I let someone into my computer and follow those steps in order.
If they charged you, dispute it with your card. If they told you your bank accounts were compromised and offered to transfer you, stop everything and read Phantom Hacker — that's the beginning of the scheme that takes entire savings accounts.
Nothing was ever wrong
Your computer is fine, your files are fine, and you didn't break anything. You saw an advertisement designed to frighten you, and it didn't work.
Now you know the one fact that makes this permanently harmless: a real problem never gives you a phone number.
Related: The fake security popup