Computer viruses come in many different forms, but if there is one thing they have in common, it is their negative effect on your computer's performance. Their effects can be of a wide variety, but this article will show you how to spot symptoms of a typical viral infection. Keep in mind, however, that even if your computer is showing some of these symptoms, it does not necessarily mean that it has been infected. These problems can be caused by hardware or software malfunctions.
Steps
Method 1 of 3: Monitor your computer's performance

Step 1. Monitor your hard drive activity
If you see the hard drive activity LED blinking or hear the hard drive spinning when you are not using any programs, there may be a virus running in the background on your computer.

Step 2. Calculate the time it takes for your computer to start up
If you notice that your computer is taking longer than usual to start up, it is possible that a virus is slowing down the startup of your computer.
If you are unable to log in in Windows, even entering the correct username and password, it is likely due to a virus

Step 3. Look at the diodes on your modem
If you see the bandwidth activity lights flashing while you are not using any program, it is possible that a virus on your computer is sending data over the internet.
Method 2 of 3: Note suspicious behavior on your computer

Step 1. Keep track of all the times your computer crashes
If the programs that you use regularly start to crash more often, it is possible that a virus has infected your operating system. You can come to the same conclusion with programs that take longer to load or run very slowly.

Step 2. Watch for popups
If your computer is infected with a virus, you may see messages appear on your screen when you are not using any program. These popups can come in the form of advertisements, error messages or the like.
A virus could also change your wallpaper without your permission. If you end up with a new wallpaper that you did not choose, it is possible that you have a virus in your computer

Step 3. Be careful when allowing programs to pass your firewall
If you receive constant requests from a program to pass your firewall, that program may well be infected with a virus and you receive these requests because the virus needs to access the network to send information to it.

Step 4. Monitor your files and folders
Many viruses erase files or folders without asking for your opinion. If you notice that some documents disappear from your computer, there is a good chance that it is due to a virus.

Step 5. Check your internet browser
Your browser may have changed the home page or are preventing you from closing certain tabs. Pop-up windows appear as soon as you launch your browser. These are unmistakable clues that your browser has been infected with a virus or spyware.

Step 6. Discuss it with your friends and coworkers
If your computer has a virus, your email contacts may have received messages that you did not send. These messages most often contain advertisements or viruses. If you learn that other people have received this type of message from you, you probably have a virus in your computer.

Step 7. Try to open the task manager
Press Ctrl + Alt + Del at the same time to open the task manager in Windows. If you cannot open it, it is possible that a virus is blocking your access.
Method 3 of 3: Get rid of a virus

Step 1. Install an antivirus
You should always have an antivirus running on your computer. If you don't have one, you can download one for free, for example AVG or Avast. Don't wait to download and install the antivirus you prefer.
- If you are unable to access the internet due to the virus present on your computer, you will need to download this program from another computer, then install it on your own computer using a USB key.
- Many websites will display advertisements claiming that your computer is infected with a virus. These are scams most of the time, you should never click on these ads. Only trust the antivirus you have installed to warn you about viruses in your computer.

Step 2. Start your computer in safe mode
You will increase the effectiveness of your antivirus by starting your computer in safe mode. To do this, restart your computer and repeatedly press the F8 key until the Advance Boot menu appears. Select safe mode from the menu that just appeared.

Step 3. Reinstall Windows
If all of your other attempts are unsuccessful and you cannot remove the virus with your antivirus, you may need to reinstall Windows using the startup disk and start from scratch. Back up whatever you want to keep and completely reinstall the operating system.
Advice
- If you are downloading something and the file name ends in ".exe", you are probably downloading a virus.
- Make a backup of your files and folders on an external hard drive or even on another internal hard drive that you can remove and keep in order to have a solution if you should lose all your data.
- Make sure your antivirus is updated regularly, don't visit weird websites, or open emails you don't know where they came from.
- Do NOT download an attachment from an email unless you know exactly what it is, this way of transmitting viruses is by far the most productive.