Reclaim Your Screen From Scammers

Q. My husband periodically receives a warning box telling us to contact Microsoft because of viruses. We cannot close it, so we turn the computer off and wait a few minutes before turning it back on. Local computer gurus have run scans three times and say that we are not infected with a virus. What can we do?

A. The persistent warning boxes sound like they are part of the ongoing blight of “tech support” scams that have plagued computer users for years. In some cases, the “virus alerts” are merely deviously scripted web pages or advertisements that can take over the screen and make it look like a realistic message to spook you into opening your wallet.

This type of ruse may not trigger an antivirus program because it is technically just a pop-up window in your web browser. Some adware programs can also fly under the radar of an antivirus tool, but an anti-malware utility like Malwarebytes or Bitdefender might be able to root out any software squatters on your system.

Even if the window is hard to close with a click, you may not have to restart the computer to ditch the message. If pressing the Alt and F4 keys on a PC (or the Mac’s Command and Q keys) does not close the program, try force-quitting the browser by pressing the Control, Shift and Escape keys to get to the Windows Task Manager — or by pressing the Command, Shift, Option and Escape keys on a Mac.

Make sure your browser is set to block pop-up windows and not to reopen the previous pages when it starts. Microsoft recommends using its newest Edge browser if you use Windows 10, but if you do not care for that program, other modern browsers can block malicious sites — or work with add-ons that do. Google’s Chrome browser has built-in tools in its settings area for removing ads, pop-ups and malware.

Microsoft, Apple and the Federal Trade Commission have information on their sites on how to spot and report tech-support scams, as does the Better Business Bureau. As always, never call a telephone number listed on the alert or supply information to the pestering site.

Personal Tech invites questions about computer-based technology to This column will answer questions of general interest, but letters cannot be answered individually.