No matter how new your computer is, it can still be a victim of random slowdowns and crashes. They slow down, sputter and stumble through your favourite sites without warning. It’s possible that your computer woes are the result of a nasty virus. How can you tell?

Here are some of the most common symptoms of computer viruses.

“Ghost” sounds

If you aren’t running any programs and your hard drive light is constantly turning on and off, or you can hear the hard drive working, you may have a virus that is working in the background.

Hijacked accounts and messages you didn’t send

Just like real-world viruses, computer viruses are on a mission to spread and infect as many machines as possible, and often the way they do this is by hijacking your email, IM, or social media accounts and sending malware-laden messages to your contacts. This is hard to detect sometimes, since most of us keep a close watch on our inboxes, but rarely stop to check your outbox. More often than not, you find out about these phantom messages from your savvy friends who see them in their inbox, realise something’s fishy, and let you know you might’ve been hacked. Just keep an eye on your Sent messages on every platform and make sure you change your account password if you notice anything you didn’t write yourself.

Modem lights going crazy

If you don’t have any programs running and your modem transfer lights are constantly blinking, you may have a virus that is transmitting data over the network. As with any other electronic equipment without anyone operating it, discovering movement and motion where no one is supposed to be is a sure sign of unwelcome activity on your computer.

Crashing, freezing, and general slowness

While system crashes, frozen screens, and painfully slow operation could be caused by poor configuration, these can sometimes also indicate that your PC is infected with malware. The best way to tell if it’s one or the other is how quickly things got bad. If your computer has gradually been getting slower over time and has now reached a point where it occasionally comes to a halt, it might be simply because you haven’t been performing regular system maintenance. Check out our guide to speeding up your PC to help speed things back up.

If your computer was running smoothly one day, and suddenly became laggy, slow, and unresponsive overnight, then there’s a chance that malicious software is the cause.

Your files do a Houdini

Viruses often delete your files and folders, or changes are made without your consent. If your documents are disappearing, there is a good chance that you have a virus. This is really scary, because you don’t really know if someone is intentionally stealing your files, scamming or engaging in cyber theft of your data… but it turns out to be a virus eating up your precious files.