How To Tell If Your Computer Has A Virus

Vectorized laptop with danger symbol on blue background. There are ways to tell if your computer has a virus.

Written by: Jay H.

Computer viruses do more than only slow down your computer – they can impact your PC’s functions, download more malware, spread to other computers, and delete or steal your files. So, learn how to tell if your computer has a virus and how to prevent them from infecting your PC in the first place.

Types Of Malware

“Computer virus” is an umbrella term for a wide range of malware that infects your PC. According to cybersecurity company Kaspersky, here are the most common variants of malware:

Computer Viruses

Computer viruses are spread from machine to machine by downloads from websites, email attachments, and shared drives. So, their spread is dependent on people sharing them.


Unlike computer viruses, worms can replicate themselves without help from people. Once a worm breaches a computer, it will spread to any network it connects to through network vulnerabilities. A worm can quickly take over an entire system, and it usually steals or deletes personal files upon executing itself.

Adware and Spyware

Adware and spyware track your information, including browsing information and location data. Your data can be sold to third parties with no regard to how it will be used.


Ransomware is an ever-growing concern, especially in the business world. This malware encrypts your data with a key known only to the attackers, then demands a ransom for their release. If you refuse, your information is encrypted permanently.

Signs Of Computer Virus Infections

Although not all malware leaves clues of infection, some signs may indicate an infection:

Slow Operations

Reduced computer performance is one of the most common symptoms of a virus. If you have windows that take a long time to load or seemingly-random processes running, it could indicate a virus. However, if you have an older computer, your PC may be slowing because of its age. If that is the case, you may want to replace your machine.

Pop-Up Advertisements

Unexpected advertisements are a common sign of malware. Not only are they annoying and intrusive, but clicking on them may install further malware on your computer. So, never click on unwarranted pop-up advertisements, even if they promise to remove malware on your system.

If you’re being bothered by these pop-ups, follow these steps:

  • Windows users: Press Ctrl + Alt + Delete at the same time to quickly open Task Manager. Then, click on the process and close it.
  • Mac users: Click on the Apple menu in the top-left corner and select Force Quit on the process.

Do note that this does not remove the infection but only closes the pop-up.

Hijacked Email

If your email contacts start receiving emails or messages from your account asking them to download or click on suspicious links, you likely have a virus. If this happens, log out of your accounts and change your passwords. Make sure you have security measures in place for your accounts, such as strong passwords as well as two-factor authentication.

Crashes And Errors

If your programs or computer freeze or crash, odd error messages appear, or applications open and close themselves, you could have a virus.

Files and Folders Modified

Unexplained changes to your files and folders, such as deleted data or changed icons and contents, don’t happen on their own. These changes could be a sign of a malicious program lurking on your computer.

Browser Redirection To Websites

A prevalent sign of a virus is getting redirected to websites that you didn’t search. These websites often encourage you to download further malware and try to obtain your personal information. So, never click on any links on the website or download any files.

Protect Yourself Against Computer Viruses

Ideally, you want to prevent virus attacks before they happen. To do this, practice good cybersecurity hygiene, including:

  • Install antivirus software and firewall.
  • Keep your software up-to-date.
  • Keep your operating system updated.
  • Do not open emails from unknown senders.
  • Avoid clicking on suspicious links.
  • Download only reputable software.
  • Keep regular backups of data.

Take steps to protect your machines from viruses. At best, they slow down your computer and bombard you with annoying pop-ups, but at worst, the damage can be much more severe.

Now that you know how to tell if your computer has a virus, it’s important to take steps if you think your machine is infected. If you need help safely removing it, contact us for support.

Read more about cybersecurity topics.


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