Signs your computer may have a virus

a laptop with a skull and cross bones flag displayed on screen

Wednesday, 21 August, 2019

Computer viruses have been with us since 1971, when a bored American IT worker created a test program and distributed it over the military’s ARPANET network.

A decade later, a floppy disc distributed the first personal computer virus, targeting Apple machines.

By the mid-1980s, hardware and software developers were engaged in a cat-and-mouse game with the spiteful souls behind viruses – which have since become a subset of malware.

While malware includes everything from ransomware to phishing and smishing, desktop computers still deploy antivirus software to repel unwanted attacks.

So how do viruses still manage to get through?

  • Many people find the day-to-day interference caused by antivirus software too restrictive, electing not to buy or install it
  • Some have endured a negative experience with antivirus utilities, which occasionally go rogue and delete valuable information
  • Antivirus and device security settings may not be high enough to prevent an attack vector getting through or being activated
  • Antivirus software can’t legislate for human error, like someone opening a macro-enabled attachment attached to a spam email from an unknown sender
  • Viruses might be hosted on compromised adware networks, corrupted webpages or other seemingly innocuous locations.

Knowing how to identify a computer virus

Appropriately-permissioned antivirus software is often able to able to tackle a rogue file on your hard drive.

You might even be able to prise it out with dedicated utilities like Spybot.

Consequently, it’s crucial to be able to identify a computer virus.

These are some of the common symptoms:

  1. The device boots and runs slowly. This is an easy way to identify a computer virus. If resources are being drained by a malicious agent, legitimate programs will run slowly.
  2. Pop-up windows appear and won’t close. This could indicate adware, especially if multiple web browsers keep loading – the ‘X to close’ facility may be booby-trapped.
  3. New software appears. This might include desktop icons, oddly named shortcuts or other signs of third-party interference. It can even redirect web browsers to strange URLs.
  4. Internet bandwidth is very slow. Available bandwidth sometimes gets co-opted into a remotely controlled botnet.
  5. The hard drive is constantly whirring when it shouldn’t. This often indicates system resources being abused, though it might be caused by a glitch in legitimate software.
  6. Unexpected error messages. If programs keep reporting errors and crashing, something may be interfering with them. Key registry files might have been corrupted or deleted.
  7. Random emails are sent and received. Email is a key distributor of viruses. Friends may receive infected messages from your account, while your inbox could fill with junk.
  8. Device protection tools won’t work. If antivirus software can’t open, or operating system updates won’t update themselves, a virus is probably preventing them from functioning.
  9. Files and folders disappear. Although ransomware tends to be explicit about what it’s done, some viruses encrypt or hide documents for devilment rather than profit.

First steps

Different viruses manifest and operate in varying ways, but we’d always recommend a few basic troubleshooting tips in first instance.

Conduct full antivirus scans with updated databases, if the software still works.

Check whether system resources are being plundered. This process varies by device and operating system; on a PC, CTRL-ALT-DEL usually brings up the Start Task Manager menu.

Reboot the computer to see if a temporary memory hole has slowed its operation or prevented programs from working.

If your PC or Mac still seems out of sorts, it’s time to request professional IT support…

Neil Cumins author picture


Neil is our resident tech expert. He's written guides on loads of broadband head-scratchers and is determined to solve all your technology problems!