26 signs that indicate your computer is infected with a virus

Many people have no idea if computer is infected with a virus until it's too late. Some of the mistakes computer users make are: not having antivirus software installed, having outdated antivirus software installed, or having antivirus software installed that they haven't been trained on.

New types of malware can be difficult to detect even by “high-quality” antivirus software, and once detected, they can be nearly impossible to remove. That’s why it’s so important to learn how to spot a potential infection before it causes significant “damage.”

These are some of the most important signs of a computer that has been infected by a virus:

1. Antivirus software indicating that there is a virus infection on the computer
2. The computer restarts randomly and unexpectedly
3. The computer does not boot into Windows, even though no software has been installed or updates have been made.
4. The Windows task manager does not open
5. Windows does not start and a message appears that says: “…system files are missing”
6. “Low memory” messages appear, even if there is no actual memory problem
7. Blue Screen Of Death occurs very often
8. Your computer appears to be “running” very slowly and your task manager may indicate high CPU usage, even when you are not running any programs (i.e., 100% CPU usage)
9. The boot or loading time of the computer to get into Windows takes a long time.
10. Pop-ups appear that redirect the browser
11. Many users receive emails from you that you did not send
12. Your broadband modem shows traffic activity when you are not using the internet
13. When new programs are installed, either they do not work or they have continuous problems
14. You suddenly receive more spam in your email inbox
15. The programs that have been installed are deleted immediately
16. Documents and files disappear (are deleted)
17. Windows updates do not install successfully
18. DVD and CD-Rom drives open and close by themselves or may not be detected by Windows
19. The sounds may play randomly, from the computer speakers
20. Files and folders do not open at all
21. Windows Security Center is disabled
22. Windows Firewall or third‑party firewall software has been disabled
23. Instead of logging into the desktop with icons after the Windows “splash screen,” the computer simply displays a black screen and a cursor.
24. Windows passwords have changed without users making any changes
25. Software, files, images, music, videos, etc. open without the user doing anything
26. The computer does not “boot” after activation