Viruses and other malware don’t always announce themselves. Some flood your screen with pop-ups, while others quietly steal passwords in the background. Knowing the warning signs means you can act quickly and limit the damage. Here’s what to look out for and what to do if you think your PC is infected.
Common signs your PC has a virus
- It has suddenly slowed down, or the fan runs hard even when you’re not doing anything.
- Pop-ups and adverts appear, sometimes even when your browser is closed.
- Your homepage or search engine has changed, or new toolbars and extensions have appeared.
- Programs open or close on their own, or the mouse moves by itself.
- Your antivirus has been switched off or won’t update.
- Friends receive strange emails or messages from your accounts.
- Files won’t open, have odd new names, or a message demands payment to unlock them. This is ransomware.
- A warning says your PC is infected and tells you to call a number. This is almost always a scam.
Some of these can have other causes, such as a failing hard drive or too many programs starting with Windows, so one sign on its own doesn’t prove an infection. Several together are a strong clue.
How malware gets onto your PC
Most infections arrive through everyday activities: opening an email attachment that looks genuine, downloading free software or films from unofficial sites, clicking a link in a text message, or plugging in a USB stick from someone else. Fake browser warnings and adverts promising to “clean” or “speed up” your PC are another common route. Knowing how it happens makes it much easier to avoid next time.
What to do straight away
- Disconnect from the internet. Turn off Wi-Fi or unplug the network cable to stop the malware sending data or spreading.
- Don’t log in to online banking or type passwords on that computer until it’s clean.
- Don’t pay a ransom or call numbers shown in pop-ups. Microsoft won’t contact you out of the blue about a virus.
- If you gave a scammer remote access or card details, call your bank straight away on the number on the back of your card. You can also report it to Report Fraud, the national fraud and cybercrime reporting service for England, Wales and Northern Ireland.
- Run a full scan. Open Windows Security, go to Virus & threat protection, choose Scan options and run a Full scan. The Microsoft Defender Offline scan restarts your PC and checks it before Windows loads, which catches stubborn malware.
- Remove unfamiliar browser extensions and reset your browser settings.
- Change your passwords from a different, clean device, starting with your email, and turn on two-step verification where you can.
When to get professional help
Call in a technician if your files have been locked, if the scan finds threats it can’t remove, if the problems come back after cleaning, or if a scammer has had remote access to your computer. Business computers holding customer data also deserve a proper check.
Our virus and malware removal service cleans the infection without wiping your files wherever possible, removes any remote-access software left by scammers, and makes sure Windows and your security software are up to date. If files have been damaged or deleted, our data recovery service can help get them back.
How to stay protected
- Keep Windows and your apps updated, as updates fix the security holes malware relies on.
- Use reputable antivirus. Microsoft Defender, built into Windows, is a good start.
- Back up your important files regularly to an external drive or cloud storage.
- Be wary of unexpected attachments, links and calls claiming to be from Microsoft or your bank.
- Use a different strong password for each account, ideally with a password manager.
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