Flashing Microsoft defender security...cant stop it

Question

Microsoft defender security is flasinig...cant log on or stop ot

Answer 1

The behavior described is typically caused by a fake “Microsoft Defender” or “Windows security” alert running in the web browser, not by the real Microsoft Defender locking the device.

To stop the flashing screen and regain control:

1. Close the browser that is showing the alert
   • Press Ctrl + Alt + Del and select Task Manager.
   • In Task Manager, find the web browser processes (for example, Microsoft Edge, Chrome, Firefox).
   • Select each browser process and choose End task until the browser closes.
   If Task Manager is not convenient:
   • Press Alt + F4 repeatedly to close the active window, or
   • Press Ctrl + W to close the active browser tab.
   • If nothing responds, hold the power button until the PC turns off, then turn it back on.
2. After restart or after the browser is closed
   • Reopen the browser.
   • Clear browsing data (history, cookies, cached files) so the malicious page does not reload from history.
   • Avoid revisiting the same link or site that triggered the pop‑up.
3. Protect against similar scams
   • Install and enable a reputable ad‑blocker extension in the browser to reduce malicious or misleading ads that cause these pop‑ups.
   • Do not call any phone number shown in such alerts and do not allow anyone remote access to the computer.
   • Microsoft does not lock the computer and demand a call via pop‑up messages.

If no phone number was called and no software was installed or remote access granted, the computer is typically not compromised and the issue is limited to the browser session.

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References:

• Disabled computer - Microsoft Q&A Computer disabled by Windows Defender Security while using FB messenger
• Microsoft Defender Scam or Do I have a virus on my computer - Microsoft Q&A I believe I have been scammed. My screen was frozen and on the screen was a number to call at Microsoft. It was a message from Microsoft Defender . Unfortunately, I did call that number and believe it was a scam. They now have my phone number and name.