How to Tell if Your Computer Has a Virus

Virus in a computer

Your computer is acting weird. Strange messages are popping up, everything has slowed to a crawl, and you can’t get your work done. Obviously, something is wrong. You fear your computer has a virus, but you’re not sure.
The first step to curing a computer virus is knowing if you have one. Sometimes it’s obvious, but other times, viruses can cause symptoms that are very similar to other common computer problems. Here are a few ways you can tell if you have a computer virus:

  1. You’re getting a lot of weird pop-up ads or error messages
  2. You’re locked out of your computer or files
  3. Your computer is suddenly running slow
  4. Your computer is freezing, crashing, or restarting itself unexpectedly
  5. Your web browser has a new homepage or toolbars you didn’t set
  6. You see unexpected icons on your desktop
  7. Your friends are getting strange messages from you
  8. You can’t access your Control Panel or other tools
  9. You’re getting alerts from your antivirus program

Let’s look at these symptoms one at a time.

1. You’re getting a lot of weird pop-up ads or error messages

When you’re browsing the web, pop-up messages are reasonably normal. Website often use pop-ups to offer coupons or downloadable content related to what you’re looking at. It’s not normal to be getting pop-ups from multiple sites at once, or tons of ads and error messages that you can’t seem to make go away. This is especially true if you aren’t currently browsing the Internet.

website pop-ups
Source: Technology Hub

Rampant pop-up messages are a dead giveaway that your computer is infected with some type of malicious software (malware). Best case, it’s just some incredibly irritating adware that’s trying to get you to click on things to generate traffic and ad revenue. Worst case, it’s spying on your computer, trying to steal your personal data and passwords.
Sometimes cybercriminals design these pop-ups to look like error messages to try to lure you into a scam. Beware of suspicious-looking error messages, especially ones that ask for your personal information or require to you pay to “fix” the problem.

error message

2. You’re locked out of your computer or files

If you’re getting strange messages that are also locking you out of your computer or files, you definitely have a virus. This type of infection is called ransomware. After encrypting your files or locking you out of your computer, hackers demand a ransom in order to restore your access.
pc virus message
Ransomware is designed to be incredibly scary and intimidate you into paying the fee, but don’t do it. Cyber criminals are not trustworthy, and even if you pay the ransom, there’s no guarantee that you will get your files back.

>Related Article: How to Deal with the Rising Threat of Ransomware

3. Your computer is suddenly running slow

If your programs are running slow, or you computer takes forever to start up, you might have a virus, especially if it happens suddenly. Of course, there are a ton of reasons why your computer might be slowing down that have nothing to do with viruses. Here are a couple of ways to check your computer’s performance to identify a virus.
Press CTRL + ALT + DELETE to open up Task Manager, or in Windows 10, search for it in the task bar.
cpu monitor
Under the Performance tab, check your CPU, Memory and Disk (hard drive) usage. If you don’t have any programs open, and any of these is constantly running close to 100%, you likely have a problem. Viruses like to install sneaky programs on your computer that run in the background and slow your computer down.
If you notice that something is hogging resources, go to the Processes tab and look for the culprit. If you’re running resource-intensive programs like Photoshop, or you have 36 different web browser tabs open, those may just be putting your computer under normal strain. But look for strange programs and processes that you don’t recognize. You’ll discover that your computer is actually running tons of processes at once, so it may be easy for virus to slip in without being noticed.

windows task manager

Another way to check if your computer is under strain is to listen for the hard drive or fans. Many hard drives have physical spinning disks that make a fair amount of noise when your hard drive is under load. Or, if your CPU is constantly running full tilt, your computer’s fans may need to work extra hard to keep it cool. If your computer is constantly making a lot of noise, even when it’s idle, you may have a problem.

4. Your computer is freezing, crashing, or restarting itself unexpectedly

Again, there are many things that could cause your computer to freeze, crash, or restart. Some of them (like Windows updates) are completely normal. Others, like hardware failures or software issues are problems, but they’re not related to viruses.
However, if you’re doing day-to-day tasks that don’t normally cause you issues, and suddenly your computer starts acting strangely, it may be infected. Make note of how often your computer freezes or crashes and what you’re doing when it happens. If it keeps happening, you may have a virus.

5. Your web browser has a new homepage or toolbars you didn’t set

Another way that malware infects your computer is by trying to hijack your web browser. Have you ever opened your browser and discovered you have a new homepage that you didn’t set? Or there’s a weird new search toolbar on your browser? These are clear signs that your computer is infected.
Like pop-up ads, some of these browser hijacking techniques are highly annoying, but not overtly harmful. In other cases, hackers can direct you to fake websites or install keylogging software to try to steal your personal information and passwords.

browser image

6. You see unexpected icons on your desktop

Viruses and malicious software love installing new programs on your computer, often without you realizing it. These are called Potentially Unwanted Programs (PUPS).
PUPS often piggy-back on 3rd party software that you actually chose to install. The problem is, hackers know most people are lazy when they’re installing software, meaning they won’t double-check all the details before clicking Install.
To avoid PUPS, only download software from legitimate sites, and avoid huge download hubs, like SourceForge. Don’t use Express Install options on software. Know exactly what the program is trying to install on your computer, and be on the lookout for pre-checked boxes that will automatically install additional programs.

7. Your friends are getting strange messages from you

Viruses want to spread and multiply. The best way for them to do that is to get into your email or social media accounts so they can send messages to your contacts and try to infect them too.
Phishing email scams are notorious for infiltrating your email contacts and sending messages to all your contacts that look like they came from you. If you suspect you’ve fallen victim to a phishing email, talk to your friends – if they’re getting emails from you that you didn’t send, you’re definitely infected.

>Related Article: Phishing Email Examples

Remember that hackers are after your social media accounts too. Facebook has seen a few scams recently that use Facebook Messenger to send a fake video that tricks users into downloading a virus.

8. You can’t access your Control Panel or antivirus tools

When they suspect they have a virus, most users either try to get to Control Panel, or check their antivirus software. That’s why the crafty viruses actually try to disable those tools.
If you press CTRL + ALT + DELETE or right click on your desktop and nothing happens, you have a problem. Check that your computer isn’t frozen, and try restarting it in Safe Mode to gain access to those tools.

9. You’re getting alerts from your antivirus program

If you have an antivirus program on your computer (which you should), and it’s doing its job, it will alert you if it detects a problem.

windows icons

Sometimes, the alert is simply that your antivirus software is out of date, so always make sure to download and install the latest updates. However, if your antivirus program does detect a virus, don’t ignore it. Let the tool scan, quarantine, or fix the problem.
Be cautious, though, not to confuse malicious pop-ups with your legitimate antivirus notifications. As we mentioned above, malware and viruses will often pretend to be error messages or virus warnings. If you have any doubt, look for your antivirus in your tray on the bottom-right side of your screen, or search for the program on your computer, rather than clicking on a pop-up.

What to do next

If you think you have a virus, use your anti-virus program to run a full scan of your computer. If it finds one, let it try to remove it for you.
Unfortunately, even the best antivirus tools can’t fix everything, and many viruses must be manually removed. If you have a virus you can’t get rid of, contact our team today. We’re here to help!

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