6 Signs Your Computer Has a Virus Right Now

Not every virus announces itself with a big red warning screen. In fact, many of the most harmful types of malware are designed to stay quiet while they do their damage — stealing passwords, collecting banking information, or using your computer to attack other systems.

Knowing the warning signs can be the difference between catching an infection early and dealing with the fallout of a serious breach. Here are the six signs I most commonly see when I arrive at a customer's home in Athol or Gardner for a virus removal call.

Sign 1: Constant Pop-Up Ads — Even When Your Browser Is Closed

If pop-up windows keep appearing on your screen even when you haven't opened a browser, or if your browser is showing ads on websites that never used to have them, you almost certainly have adware or a browser hijacker installed on your computer.

This type of malware is often bundled with free software downloads or installed when someone clicks a fake "Your computer is infected" warning. It's annoying rather than dangerous on its own — but it's a clear sign that something got onto your computer that shouldn't be there, and where adware goes, more serious malware can follow.

Sign 2: Your Browser Homepage or Search Engine Changed

If you open Chrome or Edge one day and your homepage is different — or your searches are going to an unfamiliar search engine instead of Google — a browser hijacker has modified your browser settings.

This is one of the clearest signs of an infection. Normal software doesn't change your browser settings without asking. If this happened without your permission, something installed itself and took over your browser.

Sign 3: Fake Security Warnings With a Phone Number

This one is critical. If you see a full-screen pop-up that says something like "VIRUS ALERT — Call Microsoft at 1-800-XXX-XXXX immediately" — do not call that number.

This is a tech support scam. Microsoft, Apple, and other legitimate companies never display phone numbers in virus warnings and never call you out of the blue about a computer problem. If you call the number, you'll reach scammers who will try to get you to allow remote access to your computer and pay hundreds of dollars for fake services.

If this has already happened — if you called the number, allowed remote access, or paid — call me immediately at (978) 763-6164. Acting quickly limits the damage.

Sign 4: Your Computer Is Suddenly Much Slower Than Normal

A computer that was running normally and then became noticeably slow without any obvious cause — no big Windows update, no new software installed — may be running malware in the background.

Many types of malware consume significant CPU and memory while they run, which slows everything else down. This is especially common with cryptocurrency mining malware, which uses your computer's processing power to mine cryptocurrency for someone else — while your computer struggles to do basic tasks.

Note: A slow computer can also have other causes (full hard drive, too many startup programs, aging hardware). But if the slowdown was sudden and dramatic, malware should be on your list of suspects.

Sign 5: Your Antivirus Has Been Disabled

If Windows Security (or your third-party antivirus) shows as turned off and you didn't turn it off — that's a serious red flag.

Some malware actively disables antivirus software as one of its first actions, specifically so it can continue operating without being detected or removed. If your security software won't turn back on, or keeps turning itself off, assume you have an active infection and don't continue using the computer for sensitive tasks like online banking or email.

Sign 6: Friends Say They're Getting Strange Emails or Messages From You

If someone contacts you to say they received a suspicious email, Facebook message, or text from your account — one you didn't send — your account has likely been compromised.

This can mean your email or social media password was stolen by malware on your computer, or that your account was accessed from another device using a stolen password. Either way, act immediately: change your passwords from a different, clean device, and have your primary computer checked for keyloggers or credential-stealing malware.

What to Do If You See These Signs

Stop using the computer for anything sensitive — no online banking, no email, no passwords — until it's been checked.

Do not call any phone number displayed in a pop-up. These are scams.

Run Malwarebytes if you have it. A free scan can identify many common infections.

Call for professional help if the symptoms are severe, if you've already interacted with a scam, or if Malwarebytes doesn't resolve the problem. Some malware is specifically designed to resist removal by standard tools.

Mike Cote Tech LLC provides virus and malware removal throughout Athol, Gardner, Orange, Templeton, Fitchburg, and surrounding Massachusetts towns. We remove infections in-home and via remote session.

→ Book Virus Removal or call (978) 763-6164

Hours: Monday–Friday 7:00 pm – 11:00 pm · Saturday–Sunday 11:00 am – 11:00 pm