Is your computer running slowly? Do you see strange pop-ups? Is your antivirus not working? These are all signs of a computer virus.

If left unfixed, viruses can damage or delete files, steal your passwords or personal information, change settings, or cause your computer to crash. They may even spread and infect other computers in your network.

This article covers viruses, signs of a computer virus, and how to avoid infections. We’ll also talk about what to do if your computer has a virus.

Common Types of Computer Viruses

Computer viruses come in various shapes and sizes, but they all have one thing in common: they’re bad news for your PC. The most common types of computer viruses include boot sector, memory resident, file infector, and macro viruses.

Boot sector viruses hide in a disk’s boot record and execute as soon as the system boots up. Resident viruses reside in the system memory and can run anytime your operating system loads.

Related: Types of Computer Viruses to Watch Out For and What They Do

File infector viruses typically attach themselves to executable files with .com or .exe extensions. The virus modifies or inserts malicious code into an executable file.

Macro viruses typically spread via opened Microsoft Office programs such as Word and Excel. The virus automatically embeds infectious code into the documents and spreadsheets.

Signs That Your Computer Has a Virus

malware found on computers

When it comes to determining if your computer is infected, there are many things that you should look for. Here are some signs that your computer may have a virus.

1. Computer Running Slowly

One of the most common things that viruses do is make computers run slowly, especially when you open programs or files. This might cause your computer to freeze and not respond to anything you do.

Viruses can consume a substantial amount of your system resources leading to high CPU usage. Sustained high CPU usage can make your CPU hotter than expected, leading to sluggish performance.

Related: How to Fix High CPU Usage in Windows

You may also notice that your fan is running louder than normal. This is because the CPU is working harder to keep the system cool, thus using more power.

2. Strange Pop-Ups on Screen

If you see pop-ups you didn’t authorize, it’s probably because your computer has a virus. These pop-ups can be annoying messages that contain malware.

The messages might say that your computer has been infected and that you need to call a certain phone number in order to fix the problem. Such messages might also contain a link that will take you to a website that will supposedly fix the virus.

3. Unwanted Programs or Toolbars

Viruses can try to install additional programs or toolbars without your consent to give criminals access to your system. If you notice that there are new programs on your computer have you don't remember installing, or your browser toolbar has changed, it could indicate a virus.

Also, if you start seeing unfamiliar icons on your computer, that could be another sign of a virus. The icons might have a question mark on them, and they might look different from the standard icons on your computer.

4. Files Disappearing

If files are disappearing from your computer without your permission, there is likely a virus on your system. The virus may have deleted the files, or a hacker might've encrypted them and is holding them for ransom.

Similarly, if you see messages that say that certain system files are corrupted, your computer may have a virus. This can cause the computer to crash or freeze.

Sometimes it’s email messages that disappear. If you’re unable to find emails that you were expecting, then a virus might have deleted them from your inbox. This is especially true if you don’t remember deleting them yourself.

5. Antivirus Not Working

If the antivirus program that you have installed on your system isn’t working, it’s possible that a virus deleted or disabled it. Viruses can disable your antivirus program by disabling it from the system registries.

Viruses can also access and modify your antivirus software’s configuration settings, thus altering the instructions from the registries.

Once the malware disables the program, it will allow itself to run without the antivirus scanning it. This leaves your computer susceptible to further attacks.

6. Spam Coming In From Unknown Sources

Are you receiving spam emails from addresses that you don’t recognize? Your computer may have a virus. This is because viruses can send out emails from your address without your consent.

One of the main ways computers become infected by a virus is through spam email. These emails often contain a link to a fake website, and if you click on them, an executable file will download onto your computer. This executable file is the virus itself, and it’s what installs the infection onto your system.

If you see any of the above signs, it’s important to take steps to scan for viruses and remove them from your computer as soon as possible.

How to Prevent and Remove Computer Viruses

An illustration of a bug and antivirus software

One way of preventing viruses from infecting your computer is to avoid visiting suspicious sites or clicking on links in spam emails. You should also avoid downloading pirated software or illegal material, as many contain viruses.

Scan your computer for viruses regularly and make sure that you’re running the latest version of your antivirus software. If the results come back negative, there are still ways of checking for viruses.

You also should always update your operating system and all software programs related to it as well as set strong passwords for computer access. Check processes on your computer that shouldn’t be running or if something is taking up too many resources.

Another thing to remember is to use a firewall to monitor incoming and outgoing traffic on your home network, especially if you have a broadband connection. This will help prevent outside computers from infecting your system with malware.

If you’re dealing with broken files, try restoring your PC to an earlier point in time. If the virus doesn’t seem to go away, then you might need to reset your computer to factory settings. But, only do this if it won’t affect your personal data.

If you are still having trouble with one or more viruses after trying all these options, it’s best to take your computer to a professional.

Keep Your Computer Virus-Free

The common symptoms of virus infections include slow performance, unexpected pop-ups, and new icons on your screen. One of the easiest ways to solve these problems is by running an antivirus scan to clean up the infection.

It’s also important to maintain good practices for protecting yourself from getting viruses in the future, especially if you’re not tech-savvy or don’t have much time on your hands.