How to Find Out if Your Computer Has a Virus

Two key components of the added productivity enabled by modern computers are their power and speed. By enabling you to quickly crunch large amounts of data to produce reports and figures relevant to your business, modern IT systems allow companies to operate more efficiently than ever before. Whilst malware that shuts computers down completely or hijacks their operating systems for nefarious purposes gets a lot of press, the effects of many viruses are not as noticeable. These viruses can sap the ability of your computer to operate efficiently, without displaying any obvious signs of their presence.  

At the same time, there are a number of non-virus related reasons your computer could be providing subpar performance, such as an excessive start-up program load and program bloat, where the computer’s resources are insufficient to properly handle the demands placed on it by a multitude of solutions. In this blog, we outline steps you can take to determine if your computer is in fact infected by a virus, as opposed to some of the other operational issues which might negatively affect its performance.

Some actions you can take to determine if a virus is active on your computer are as follows:

Evaluate computer performance

Monitor hard drive activity: If no programs are being run on your computer and yet the hard drive light continues to turn on and off, or you can hear it working, this can be a sign that a virus is operational in the background.

Excessive computer boot up time: A computer taking substantially more time to boot up than it previously did can indicate that a virus is slowing down the process.

Blocked log-in: If you are unable to log-in to Windows, a virus may have taken over the long-in screen.

Data transfer activity: If no programs are running and your modem transfer indicator lights continually blink, it may be an indication that a virus has hijacked the computer to transmit data over your network.

Monitor program activity

Keep track of program crashes: If you notice that the programs you utilise regularly begin crashing more often, it may be the result of a virus infecting the operating system. Other signs that this has occurred include programs taking longer to load, or operating very slowly.

Be on the lookout for popup messages: Viruses will sometimes propagate popup messages to your screen that try to get you to buy something or prevent you from accessing your web browser or simulate system error messages. When surfing the web, popups can be a normal part of the experience, but when popups appear at times when your browser isn’t open this is typically a sign of adware, spyware, or scareware. The latter type often takes the form of a message proclaiming that a virus has been detected and urges you to buy software to get rid of the virus. Doing so at best wastes money and at worst buys even more malware.

Watch for phantom messages: Some viruses hijack your computer for the purpose of sending messages using your system. These can be for the purpose of advertising an item or even for trying to convince your contacts to send money to those behind the virus. If you begin to see responses from your friends to emails you never sent or other strange messages, it may indicate that a virus has hijacked your computer and is sending out emails in your name. If this happens, make sure to change your password right away to prevent further email distribution from a virus that has stolen your password.

Don’t grant programs firewall access easily: Unless you are reasonably certain that a program is safe, be very cautious about granting it firewall access. Furthermore, if you are constantly getting messages that a program is requesting firewall access, this can be a sign that the program is infected and is trying to send data using your router.

Keep track of your files: A virus can delete or otherwise alter your files and folders, sometimes even encrypting them so you can’t access them. If this happens, or you see files disappearing for no reason, it can be a good indication that you have a virus.

Open your web browser: If your web browser takes you to a new home page, or doesn’t allow you to close tabs it can be the result of a virus taking over your system. The same applies if popups appear immediately when you open the browser.

Attempt to open Task Manager: By pressing Ctrl+Alt+Del you can try to open Windows Task Manager. If you aren’t able to do this, the cause may be a virus blocking your ability to use this function.


Computer viruses, or malware, have grown in complexity and scope in recent years. The most dangerous of these viruses attempt to remain hidden on your system for as long as possible. In some cases, malware can remain on a system undetected for months at a time if efforts are not taken to discover and remove it. The steps outlined above can be used on a regular basis to help you identify any viruses that may have infected your computer. Once this is done, you can use your anti-virus software or take other actions to remove the threat, including seeking outside expertise if necessary.