One day everything’s running smoothly, and the next your computer slows to a crawl or starts acting strangely. While performance issues can have many causes, these warning signs may indicate your device has picked up a virus or malware infection.
1. Your Computer Suddenly Slows Down or Crashes
A major red flag is when your system starts freezing, crashing, or running unusually slow. Malware can consume your device’s memory and processing power, leaving fewer resources for everyday tasks like browsing, streaming, or working in apps.
Try this:
- Restart your device and close background apps.
- Run a full antivirus or anti-malware scan using trusted software such as Microsoft Defender, Malwarebytes, or Norton.
- Keep your operating system and security updates current.
2. You Notice Unusual Activity When You’re Not Using It
If your laptop fan runs constantly, your device heats up for no reason, or indicator lights flicker when you’re not doing anything, your computer might be running hidden background processes.
Try this:
- Open your Task Manager (Windows) or Activity Monitor (Mac) to check for unknown programs using CPU or memory.
- Disable suspicious startup programs.
- Uninstall any software you don’t recognize.
3. Strange Pop-Ups, Warnings, or New Icons Appear
Pop-up ads, unexpected toolbars, or new desktop icons you didn’t install could signal adware or malware. Be especially cautious of “urgent” virus alerts that try to get you to download a fake fix — those are often part of the scam.
Try this:
- Don’t click on suspicious pop-ups or links.
- Run a browser cleanup or reset your default settings.
- Use built-in browser tools to remove unknown extensions or add-ons.
4. Your Security Tools Stop Working
Some viruses disable antivirus software to avoid detection. If you can’t update or open your security program — or can’t visit security websites — it could be a sign your system is infected.
Try this:
- Restart in Safe Mode and run a virus scan from there.
- Use an offline virus removal tool from a trusted vendor.
- If the problem persists, contact a professional for cleanup support.
5. New or Updated Threats to Watch For
Today’s online threats go beyond traditional computer viruses. Keep an eye out for these, too:
- Phishing scams that steal login details through fake emails or texts.
- Ransomware that locks your files until you pay a fee.
- Fake software updates that install malware.
- Malicious browser extensions that collect data or redirect your searches.
- Mobile device malware, especially from unofficial app stores.
5. Stay Protected
The best defense is prevention:
- Keep your system and software up to date.
- Use a reputable antivirus and firewall.
- Avoid clicking unknown links or downloading files from unverified sources.
- Back up important files to the cloud or an external drive.
If your computer is showing multiple warning signs or you can’t remove the infection, contact a trusted tech support professional or your device manufacturer for assistance.