7 Signs Your Computer
Has Been Infected With Malware
Here's the uncomfortable truth I've learned after 25 years of fixing computers: most people don't realize they're infected until the damage is already done. Modern malware is built to stay quiet — it doesn't want you to notice it. But it almost always leaves fingerprints. Here are the seven warning signs I tell everyone to watch for, starting with the subtle ones and working up to the serious stuff.
1 Your Computer Suddenly Got Slow
A machine that was fine last month and now takes forever to boot, lags when you type, or runs its fan constantly is a classic early warning sign. Malware runs in the background using your processor and memory — often to mine cryptocurrency, send spam, or quietly shovel your data somewhere. To you, it just feels like your computer is tired.
Open Task Manager with Ctrl + Shift + Esc and click the Processes tab. Sort by CPU and memory. If something you don't recognize is eating 30%, 50%, or more — and it's not a Windows process or a program you opened — write down the name and search it. A slow PC has plenty of innocent causes too, but a sudden, unexplained slowdown deserves a malware scan.
2 Pop-Ups and Ads Showing Up Everywhere
I'm not talking about the normal ads on websites. I mean pop-ups that appear on your desktop when no browser is open, ads that show up on sites that never had them, or alarming "YOUR COMPUTER IS INFECTED — CALL THIS NUMBER" warnings. That last one is the scam itself — the only thing infected is whatever clicked the bait. This kind of malware is called adware, and it's one of the most common things I remove.
Never call the number in a pop-up and never click "fix now." Close the window (or your whole browser) and run a scan. Malwarebytes is excellent at clearing out adware that regular antivirus sometimes misses. While you're at it, check your browser extensions and remove anything you don't remember installing.
3 Your Browser Homepage or Search Engine Changed
You open your browser and your familiar homepage is gone, replaced by some search site you've never heard of. Or you search for something and the results come from a strange engine full of sponsored junk. This is called browser hijacking, and it's malware redirecting your traffic so someone can profit from your clicks — or steer you toward more dangerous pages.
Go into your browser settings and reset your homepage and default search engine back to what you want. Then check the extensions list again and remove anything suspicious. If the hijacker keeps coming back after you change it, that's a strong sign there's deeper malware reinstalling it — time for a full scan.
4 Programs You Didn't Install Are on Your Computer
New toolbars, unfamiliar apps, or icons on your desktop that you never put there are a red flag. Malware often bundles other malware, or quietly installs "helper" programs that do anything but help. If you see software you don't recognize and definitely didn't download, treat it as guilty until proven innocent.
Search "Add or remove programs" in the Start menu and look through the list, sorted by install date. Anything you don't recognize from around the time the problems started is worth investigating before you uninstall it — a quick search of the name will usually tell you if it's legitimate or not.
5 Your Antivirus or Task Manager Is Disabled
This one is a big deal. Some of the nastier malware out there actively shuts down the tools you'd use to remove it. If you go to open Windows Security and it won't launch, or Task Manager has been disabled "by your administrator" when you're the only person who uses the computer, something is deliberately blocking your defenses. Healthy software doesn't do this — malware does.
Malware that disables your security tools is usually well past the casual-adware stage. Don't keep using the computer for banking, shopping, or anything involving passwords until it's cleaned. If you can't re-enable your antivirus or it gets shut down again immediately, this is the point where I'd stop and get professional help rather than risk making it worse.
6 Friends Are Getting Strange Messages From You
If people tell you they got an odd email or social media message from your account — a weird link, a request for money, a "check out this video" you never sent — your accounts or your computer may be compromised. Malware and account hijackers love to spread by impersonating you to everyone in your contacts, because people trust messages from someone they know.
Change the passwords on the affected accounts immediately — but do it from a device you trust, not the infected one (a phone is fine). Turn on two-factor authentication wherever it's offered. Then scan the computer, because if malware captured one password, it may have captured others.
7 Your Files Are Locked or You See a Ransom Demand
This is the worst-case scenario. Your files won't open, their names have been scrambled or given a strange new extension, and a message appears demanding payment — usually in cryptocurrency — to get them back. This is ransomware, and it's exactly as bad as it sounds. It's also, sadly, one of the most common serious infections I get called about.
Disconnect the computer from the internet right away (unplug the network cable or turn off WiFi) to stop it spreading to other devices or your cloud backups. Do not pay the ransom — there's no guarantee you'll get anything back, and paying marks you as an easy target. If you have a clean backup, your files may be recoverable. Either way, this is a situation where getting a professional involved early can make the difference between losing some files and losing everything.
Think You're Infected? Don't Wait It Out.
Malware rarely gets better on its own — it spreads, digs in deeper, and the longer it sits, the more it can grab. If you've spotted one or more of these signs and a scan isn't clearing it, or you're locked out of your own security tools, that's the moment to bring in someone who does this every day.
If you're in the Nanaimo, BC area, BigMike Computer Services has cleaned up every kind of infection on this list, from sneaky adware to full-blown ransomware. A quick call or email can tell you how serious it is and what your options are — often before any damage becomes permanent.
Visit BigMike Computer Services →— BigMike | Computer Repair Technician, Nanaimo BC
📧 BigMikeNanaimo@gmail.com